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Chapter 2: The U-boat in the Atlantic and the Bay

On 1st August, 1943, Sunderland ‘B for Baker’ of No. 10 Squadron, Royal Australian Air Force, was on patrol above the Bay of Biscay flying at 1,700 feet over tumultuous seas beneath a cloudy sky. About 1630 hours her look-outs saw ‘five sloops and a Catalina engaged in a U-boat hunt’. The captain of ‘B for Baker’ decided to take a hand and had just altered course to do so when he ‘sighted a U-boat two miles away on the starboard bow’. The submarine was some six miles from the nearest sloop and was moving on the surface at a speed of about ten knots. ‘B for Baker’, making a tight turn, attacked from the U-boat’s starboard quarter at an angle of sixty degrees from her track. During the run in, that most perilous of moments—for if the depth charges were to be accurately dropped it was necessary to fly straight and level—she came under heavy 20-mm. cannon fire. This was returned by the Sunderland’s forward gunner, but soon the flying boat was in trouble. First the inner port engine was hit and then, when there were still some 400 yards to go, the starboard main fuel tank was pierced and petrol poured into the cockpit in which sat the captain and his two co-pilots, all three of whom were by then seriously wounded. Despite the petrol and the pain, they flew on and from a height of fifty feet dropped six depth charges of which three fell on one side and three on the other of the target. The foam and spray of the explosions had scarcely melted when the rear gunner ‘saw the U-boat lift out of the water and then sink by the bows’. ‘B for Baker’ was also mortally wounded. Her captain made for the sloops, but was forced to set down before he reached them. The Sunderland bounced heavily twice and then began to settle. In a few moments the starboard mainplane broke away with six of the crew upon it. They were picked up by the sloop, Wren, and twelve of the survivors of the U-boat were rescued by HMS Kite.

The destruction of U.454 was a single incident in the long drawn-out Battle of the Bay in which both the Royal Navy and the Royal Air

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Force were involved. To wage the twin battles of the Bay and the Atlantic was Coastal Command’s main task and its main contribution to victory.

Early in 1943 the Allies were so well aware that the war could not be won unless the menace of the U-boat was countered, that they regarded the fight against enemy submarines as the most important of the tasks laid upon their sea and air forces. This view, it will be remembered, was expressed very forcibly at the Casablanca Conference and found clear expression in its directives. By May, 1943, Air Marshal Slessor had been at the head of Coastal Command for some three months. He had in his hand the weapon which his predecessors had forged. It was now for him to use it with vigour and address.

There were two transit routes which took the U-boats from their bases in Europe to the Atlantic. One of these lay between Iceland and the north of Scotland, and the other through the Bay of Biscay. Before considering the fortunes of those engaged in the battle on and above both these routes, it will be convenient to glance at the general manner in which Coastal Command conducted its operations. They were based as far as possible on three general principles: concentration of the maximum force at the decisive time and place; determination to win and keep the lead in the scientific and technical fields; and maintenance at the highest pitch of the standard of training, both in the aircraft and outside it. Concentration had to be achieved both strategically and tactically; in other words, all antisubmarine units had to be used and deployed with effective economy while being at the same time so concentrated that overwhelming force would be present at the crucial point and moment. Obvious though this may seem in theory, to attain it in practice was far from easy.

The general system of control and direction had at its head the Anti-U-Boat Sub-Committee of the War Cabinet, with the Prime Minister in the chair. ‘It was’, records Slessor, ‘an invaluable organization when the situation was really critical in the air/sea war’. This Sub-Committee handled all matters of policy, and being in supreme authority, could instantly impose its will on any Ministry or Headquarters. Even more important, perhaps, was the power it had to bring together round a table those who were responsible for the conduct of the war at sea. It was attended either in person or by proxy by such American leaders as Mr. Harriman and Admiral Stark, who received all its papers and could, if necessary, take a full share in its decisions. On paper, at least, this controlling body seemed incapable of improvement. In practice, however, this was not so,

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and in point of fact wholly efficient Anglo-American control was never achieved.

It was not from want of trying. From December, 1941, when the Japanese attack on Pearl Harbour brought America into the war, the C.-in-C. of Coastal Command, at that time Air Marshal Joubert, had not ceased to press for a unified command, at least in the Battle of the North Atlantic. His proposals, though agreed by the United States Naval Staff in London, had not found favour with the Chief of the United States Navy and had not been adopted. Slessor, when he arrived to take command, found this situation unchanged. He at once advanced the proposition that the Atlantic Ocean was ‘one battlefield in which the Allies—Britain in the east and the United States and Canada in the west—were fighting an entirely mobile enemy’. The position of Germany solidly entrenched on the right flank of the battlefield, the large number of bases on that flank at her disposal, the nature of the weapon she was using, all enabled her to switch attacks to whatever point she desired with the minimum of delay and the maximum of concentration. In a matter of days Dönitz could move his U-boat fleet from the American seaboard to the Mediterranean approaches, or northwards to the stormy seas about the coasts of Iceland. So flexible a mode of attack, Slessor maintained, required an equally flexible mode of defence, and thus demanded a ‘close-knit system of control’. Progress towards it was certainly made, but in the closing stages of the war that close co-operation, ‘a commonplace in other spheres’ of air warfare, had not been fully established over the uneasy waters of the Atlantic.

The Allies came near to falling into an error as old and hoary as war itself; they sought, if not to be strong at all points simultaneously, at least to have great strength available at what to each separately were important points. This led them to station too many antisubmarine craft at some places (for example, the seacoast of the United States), too few at others. Not until June, 1943, after the matter had been strongly debated both in London and in Washington and Slessor had paid a personal visit to the United States, were any American air squadrons so redeployed as to take their full share in the battle. When they did so, they were well handled and achieved instant success.

An efficient system of control is very hard to establish in a war fought by nations in alliance. Yet at first it seemed that over the wide Atlantic the aircraft of both Britain and America would play their part in accordance with an exact and common plan drawn up and applied in common. An Atlantic Convoys Conference held in Washington in March, 1943, attended by Air Vice-Marshal A.

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Durston, Slessor’s Senior Air Staff Officer, was prodigal of results. It reorganized the system of convoy routeing and escorting, though perhaps not as completely as could have been wished; the Eastern Air Command at Halifax accepted full operational control over all anti-submarine aircraft based in Canada, Labrador and Newfoundland, whether Royal Canadian, Royal Air Force or American; an Area Combined Headquarters was established at St. Johns, Newfoundland. Even more important was the undertaking entered into by the United States to base very long range anti-submarine aircraft in Newfoundland, to transfer a number of similar aircraft to the Canadian Air Force and to establish a Combined Procedure Board. This Board met in St. Johns early in June with the object of setting up a single joint system ‘of operational intelligence and signals procedure for use by all Allied anti-submarine squadrons in the Atlantic’. It was, said Slessor, a ‘rudimentary measure of common-sense’, and its effect would have been to enable British, American and Canadian squadrons to operate without special training or ‘indoctrination’ anywhere in the area at any moment.

The proposed procedure, however, was never adopted. Perhaps it was too simple, perhaps it demanded a higher degree of coordination than it was then possible to achieve, but for lack of it two great air and sea powers fought a desperate battle for more than three and a half years in conditions which the absence of full understanding between them rendered unnecessarily arduous. For one moment it seemed that the Combined Procedure Board would produce a combined scheme. An agreement recommending its adoption was indeed within sight of conclusion when the American Navy Department stepped in and brought the labours of the Board to an abrupt end.

A similar fate befell the Allied Anti-Submarine Board, formed to achieve closer co-operation on more general lines. Composed of four officers, two British and two American, the air and the sea being equally represented, it was sent upon an extensive and exhausting tour of the anti-submarine commands in all theatres of war. In a comparatively short space of time it covered thousands of miles and produced a number of recommendations. No notice was taken of them and they remained stillborn.

The probable explanation of this state of affairs is that, despite all that the higher command of the United States Navy had averred at the Casablanca Conference, they were, very understandably, far more concerned with the great offensive sea and air campaign in the Pacific than in defensive operations conducted against submarines in the Atlantic. They could not, and did not, entirely ignore that

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theatre, where operation ‘Bolero’, by which American troops and American equipment were brought to Britain in an ever-increasing stream, was in progress throughout 1943. A number of American light escort carriers, Card, Core, Bogue, Block Island and Santee whose duty, nobly carried out, was to protect convoys were soon as well known in the Operations Rooms of Northwood, Plymouth and Liverpool as were the ships of the Royal Navy; but the Americans showed a tendency to keep powerful, and as it turned out quite unnecessarily powerful, anti-submarine forces in the areas close to their own Atlantic seaboard. They were also much concerned for the safety of their convoys in the approaches to the Mediterranean. A study of the orders issued and the plans propounded makes it difficult to escape the conclusion that Admiral King and his staff did not view the Battle of the Atlantic in the same light as General Marshall viewed the invasion of Europe in 1944.

How difficult was the problem may be seen from what took place in the Mediterranean approaches early in 1943. In the previous autumn, during operation ‘Torch’, the landings in North Africa, control of the Royal Air Force station at Gibraltar had been temporarily transferred from Coastal Command to the Air Officer commanding in French North Africa. Such a decision was as correct as it was obvious. By May, 1943, however, Tunis had fallen, the campaign was at an end and the reasons for this arrangement no longer existed; but the Battle of the Atlantic was still raging and the return to Coastal Command of operational control of the squadrons at Gibraltar had, in consequence, become of increasing importance. The collapse of the Axis forces in North Africa had brought the Allies a sufficient number of bases for the Mediterranean Air Commander to provide adequate escort in that sea where, indeed, the submarine activities of the enemy had fallen into a rapid decline. Nevertheless, not until 8th October, 1943, when an air base was established in the Azores as the result of an agreement between Great Britain and Portugal, and a force under Air Vice-Marshal B. G. Bromet installed therein, were the Gibraltar squadrons returned to Coastal Command.

Yet another problem faced Slessor. At the end of 1942, the personal intervention of Mr. Stimson, the American Secretary of State for War, had caused the United States Army Air Force to set aside two squadrons, equipped with the latest version of the Liberator, to carry out anti-submarine operations off the coast of Morocco. Slessor, who was in Washington at the time, urged that they should be stationed within the area of No. 19 Group of Coastal Command, then operating off the south-west coasts of England. His view

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prevailed, and in due course the two squadrons arrived at St. Eval in Cornwall. They soon proved their value because of their great range, and were about to play a major part in the patrols across the Bay of Biscay, known as ‘Outer Gondola’, and had indeed already destroyed one U-boat, when suddenly they were ordered to Lyautey in Morocco.

By that date the United States Navy Department had set up in Casablanca the headquarters of what was known as the Moroccan Sea Frontier. The effect of this decision was to establish a zone of American responsibility in between two British areas, one at Gibraltar, the other in West Africa. The American Officer Commanding the Moroccan Sea Frontier was in a position of complete independence. He had his own intelligence staff, which frequently provided him with information on the movements of U-boats differing markedly from that which the Air Officer Commanding at Gibraltar received from British sources. The American commander persistently used the long-range aircraft at his disposal for the escort of convoys classified by Admiralty intelligence as unthreatened, and for anti-submarine sweeps in areas where, if that intelligence was correct, and it was, no U-boats were operating. Our ally preferred to give local protection, in the widest sense of the term, to ships approaching Casablanca rather than to send aircraft to the Bay of Biscay where the British were convinced the U-boats were most vulnerable. This state of affairs, which the Allied Antisubmarine Board’s recommendations might have prevented had they been accepted, endured throughout 1943 and no effective cooperation was achieved until 1944. The consequence was that the forces engaged in the critical Battle of the Bay of Biscay were deprived of a number of aircraft at a time when their presence there would have been invaluable.

On the conduct of the air war in the Atlantic the views of the American Government seem certainly to have been divided. The biographer of Mr. Stimson has described the concern felt by this great Secretary of War, and it was he and his lieutenant, Mr. Robert A. Lovett, the Under Secretary, who proposed, in the early summer of 1943, that there should be one Allied Air Commander-in-Chief with authority over all Allied anti-submarine air forces in the Atlantic area. The proposal was at first sight attractive, but it found little favour with the British Cabinet, nor was Slessor eager to take the post even though the Americans were ready to put forward his name. The fate which had befallen the Allied Anti-Submarine Board was vivid in his memory and he convinced himself that an Air C.-in-C, Atlantic, would be no more than an impotent figurehead, not an

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active officer whose orders would be obeyed without question by all Allied formations engaged in the battle. That the American suggestion was made in good faith is as indisputable as the question whether its adoption would have led to the consequences Slessor feared is unanswerable. We shall never know. All that can here be recorded is that the C.-in-C, Coastal Command, preferred rather to bear the ills he had than to fly to others he knew not of, and he therefore opposed the creation of the post.

The British Admiralty proved far more accommodating than the American Navy Board. In all Area Combined Headquarters, at the headquarters of Coastal Command itself and in the Admiralty, naval and air force officers worked closely together in a spirit of harmony and understanding. The legacy of suspicion engendered by decisions in 1941, which had placed Coastal Command under the operational control of the Admiralty, gradually disappeared and relations between the two Services could scarcely have been more cordial. This most fortunate state of affairs was in large measure due to Slessor and his predecessors and to Admiral Sir Max Horton, who had been one of the most daring and successful submarine commanders in the First World War. He was concerned entirely with the Battle of the North Atlantic and to his understanding of the problems of the air were added the untiring efforts of two other naval officers, Rear Admiral P. Brind, the Assistant Chief of the Naval Staff (Home Operations) at the Admiralty and Captain D. V. Peyton-Ward, Senior Naval Staff Officer at Northwood, the Headquarters of Coastal Command. Even more than Horton these two men thoroughly understood the possibilities and limitations of aircraft and were at all times ready to see that they played their proper part in the battle.

Yet the course of true love never did run smooth, and there were still occasions, as, for example, when routeing and diverting convoys, when the Admiralty was liable to act without consulting Coastal Command. On the whole, however, the system of control and command, which had been devised before the war, stood the test and worked well.

After some delay and discussion, the procedure known as ‘Stipple’, which in a primitive form had been in operation for some time, was enlarged and expanded. In May, 1943, Slessor informed the Anti-U-Boat Sub-Committee that he could no longer find escorts for every convoy whether passing through a dangerous area or not. In consultation with Admiral Brind, he suggested that, in future, convoys considered liable to attack should be given air cover, while those thought to be reasonably safe were to be left to the care of

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their surface escorts. The convoys for air protection were chosen at the tripartite conference held every morning on the ‘scrambler’ (secret) telephone between the Headquarters of Coastal Command, those of the Western Approaches at Liverpool, and the U-boat Intelligence Department of the Admiralty. The latest information was available to this daily conference which took the decisions affecting the protection of each convoy.

Such were the difficulties and achievements behind the scenes; those which confronted the squadrons fighting the battle were of a different kind. The right type of aircraft fitted with the right type of special radar equipment was very scarce. No. 120 Squadron had been re-equipped with the Mark I Liberator, of very long range, in 1942. Wastages were to be replaced by Marks II, IIIA, and V, which latter type were to be the aircraft allotted to Nos. 59 and 86 Squadrons. The fitting of long-range tanks, however, in both Marks II and III Liberators proved to be a slow process and this adversely affected the supply of these essential aircraft. The installation of the ASV Mark III also took time. By February, 1943, a few aircraft of No. 224 Squadron possessed the American type, the Mark IV, by March No. 172 Squadron flying Leigh Light Wellingtons had been equipped with the British Mark III, more squadrons received it during the following month and the Halifax squadrons by early summer.

There was a sharp divergence of view between Whitehall and Northwood concerning the number of long-range aircraft necessary to bring the U-boat campaign to a standstill. The operational research scientists in the Admiralty, a most valuable body of men, were of opinion that to achieve this end at least 260 would have to operate in the Bay of Biscay. At that time, the spring of 1943, only 70 were available in No. 19 Group, though Slessor was already strengthening Bromet’s hand in the Bay by concentrating additional squadrons from other Groups. The Admiralty, however, submitted a demand for an additional 190 Lancasters which could only have been met by diverting aircraft from Bomber Command, at that time ‘the only British force exerting a direct pressure on the enemy’. In this matter, Slessor, to his great regret, found himself in opposition to Sir Dudley Pound, the First Sea Lord. The Air Marshal was a convinced supporter of operational research, but he considered that the figure proposed by the scientists was based on a number of arbitrary and unjustified assumptions. He said so frankly and went on to point out that it was, in his view, impossible to forecast the outcome of a battle or to decide the forces necessary to win by, as he put it, ‘doing sums’. Even had the additional 190 first-line

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aircraft been available, it would not have been possible to fit them with special equipment or to provide them with trained crews in time to influence the critical situation in the Atlantic.

Slessor’s opposition to the proposals of the scientists did not mean that he was satisfied with the situation. On the contrary, he urged that the Allied strength in the Atlantic should be redeployed and asked that six additional long-range squadrons, seventy-two aircraft in all, should be transferred from America to the United Kingdom, where they could be used to take part in the Battle of the Bay. His views were shared by the Anti-U-Boat Sub-Committee, nor was the American Admiral Stark unfavourable to the project. In the third week of April, a memorandum signed by Pound, Stark and Slessor was laid before the Combined Chiefs of Staff. Not until June, however, after Slessor had argued his case once more in Washington, did the first American squadrons arrive in Cornwall. They never reached the hoped for total of six, but by January, 1944, there were three naval Liberator squadrons (thirty-six aircraft) operating from England, and for a time one Catalina flying boat squadron. Two of these had taken the place of the 4th and 19th Squadrons of the United States Army Air Force which had been transferred to Morocco. Unfortunately, for a variety of reasons, the U.S. Navy squadrons did not get into action in time to play any great part in the Battle of the Bay until after its climax.

Co-operation with Canada was always smooth and easy. Air Vice-Marshal G. O. Johnson, commanding at Halifax, eagerly fell in with Slessor’s plans, adopted the ‘Stipple’ procedure, and kept in the closest possible touch with Northwood. Nos. 422 and 423 Squadrons of the Royal Canadian Air Force operated from Northern Ireland and No. 162, flying amphibian Catalinas, from Iceland, though this squadron of the Royal Canadian Air Force did not come into action until February 1944.

Such, then, was the general situation in the Command when in the spring of 1943 it addressed itself with renewed confidence to the duty of protecting our convoys. This meant the seemingly endless task of destroying U-boats. Endless was, in truth the word, for this warfare, waged so relentlessly, began on the first day of the war when the Athenia was torpedoed, and ended on the last, when a U-boat sank two ships in the Firth of Forth. The two main theatres of operations were the Atlantic and the Bay of Biscay; but it must not be forgotten that every action fought in one or the other was part of one general battle, the Battle of the Atlantic, in which the intensity of the conflict fluctuated with every change in the disposition of the U-boat forces at the disposal of Dönitz and the German

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Admiralty. During the early part of 1943 and up to the middle of May the weight of the enemy’s attack was still to be felt in the North Atlantic. In this dreary waste of ocean he appeared for the moment, at least, to have gained the upper hand. The method he used was to attack convoys with large packs of U-boats and in an action fought from 16th to 20th March one of these achieved a signal success against two convoys, HX.229 and SC.122. At dawn on the 16th in heavy weather, a U-boat belonging to the Raubgraf pack picked up convoy SC.122. Others were summoned to the scene and by the evening most of the pack were present and able to make a determined assault. At 0200 hours on the 17th four ships were torpedoed in quick succession and during that day a fifth met her fate by the same means. Two Liberators from Ireland had been able to spot four of the attackers, but on one occasion the depth charges failed to release. A third Liberator was unable to find the convoy and returned to base after a flight of over twenty hours where it made a forced landing without injury to the crew. Night drew on, the U-boats maintained their attack and two more ships were sent to the bottom. On 18th March, three Liberators from Ireland and two from Iceland covered the convoy from 1038 hours until 2038 hours. They made six sightings of U-boats and carried out four attacks; their presence certainly prevented further assaults upon the battered convoy. Night passed uneventfully, but in the early hours of 19th March, while it was yet dark, another ship was sunk. That day was a repetition of the previous, the convoy being protected by three Liberators, three Fortresses and three Sunderlands, of which one saved a tanker ‘from almost certain destruction’. The pilot sighted a periscope during the mid-morning hours, but it was too far off to enable him to deliver an attack. Later the U-boat was sighted again, this time barely six miles from the tanker which was lagging behind. The Sunderland attacked and the U-boat was forced to dive. In the words of the Senior Naval Officer in charge of the convoy’s escort, ‘These aircraft were a tremendous asset to the escort in preventing day shadowers’. Unfortunately, not being equipped on any large scale with Leigh Lights, the aircraft of Coastal Command were not able to be of assistance during the hours of darkness, though at that time of the year in those latitudes it was possible to remain with the convoy until 0200 hours.

How closely the aircraft worked with the Navy and with the ships they were both protecting can be seen from this extract from the Report of the Senior Officer, Escorts, at that time.

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1845/19—Aircraft called on 2.410 kilocycles asking if there was anything for him. He was remaining until 0200.

1850—Aircraft told to investigate 287° 10 miles.

1926—Aircraft reported he had attacked U-boat 280° 45 miles.

2150—Aircraft told to investigate contact 224° 5-10 miles.

2236—Aircraft reported he had investigated and made two contacts which disappeared; also found a straggler bearing 215° 45 miles.

2336—After further bearings in same area aircraft told to search again 3-10 miles. Aircraft reported U-boat 240° from convoy 9 miles. Attacked by aircraft with machine-gun fire, bomb doors failing to open in time.

0142/20—Aircraft asked for further instructions and told to investigate astern.

0155/20—Aircraft reported straggler 225° 14 miles, and contact on same bearing 20 miles. Aircraft then reported leaving.

During 20th March the presence of the U-boats was still manifest, but by then the air escort had been increased and three Fortresses covered the convoy continuously for nearly thirteen hours while ten Sunderlands carried out a sweep close by to cover not only convoy SC.122 but also HX.229, which, composed of faster vessels, was closing on it from astern. In this sweep ‘T for Toe’ of No. 201 Squadron found a U-boat on the surface and sank her, and ‘Z for Zebra’ of the same squadron damaged a second. In the meantime convoy HX.229 was drawing near on a converging course. There were in it forty ships steaming in eleven columns. The first attack upon it occurred on 16th March when a ship was torpedoed in the evening. This was followed almost immediately by the loss of three more. The third and fourth attacks took place on 17th March early in the morning. Three ships were torpedoed. These casualties were caused while the convoy was still out of range of air cover. Dawn on the 17th found the commodore in charge of it very anxious. The U-boat pack was obviously increasing in strength and to counter it only the surface escorts were available. At 1305 hours his fears were justified and two more ships were torpedoed. By then the convoy was reaching a point at which it could be given air cover from extreme range. Unfortunately there was a strong wind blowing across the runways in Iceland and it was not until 1655 hours that ‘J for Johnnie’ of No. 120 Squadron based on Iceland was able to reach the convoy and provide escort for four hours. ‘Its advent’, records the Senior Naval Officer, was ‘a very welcome sight’. During its patrol, ‘J for Johnnie’ attacked three U-boats with depth charges and one with machine-gun fire. On the 18th a gale sprang up, visibility fell to two miles and the escorting aircraft failed to find the convoy. Taking advantage of the bad weather, the U-boats renewed their attack and sank two ships in the afternoon. On 19th March the commodore could breathe more

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easily. His sorely harassed charges were now well within range of Coastal Command. Three Liberators and four Fortresses covered the ships for twelve hours and on the next day their place was taken by three Fortresses, while Sunderlands made sweeps in the neighbourhood. This round of the battle ended to the advantage of the enemy. ‘This is so far the best result obtained in a convoy battle’, noted the German Admiralty in its War Diary. Twenty ships had been sunk. The situation was very serious.

Nevertheless, the tide was on the turn. The Atlantic Convoys Conference in Washington, which, it will be remembered, Air Vice-Marshal Durston, Slessor’s Senior Air Staff Officer, had attended, reorganized the system of convoy control and escorting and soon shipping losses began to fall.

Then came the decisive month of May, when the enemy losses reached a peak. In that month, no less than 41 U-boats were sunk. Of these, 28 were lost around mid-Atlantic convoys—six being put down in attacking convoy ONS.5 on the night of the 5th/6th. Between the 19th and 21st May convoy SC.130 went through a very large pack of U-boats without loss, Coastal Command aircraft obtaining thirty sightings, one, ‘P for Peter’ of the indefatigable No. 120 Squadron, making eight in one sortie. British and American auxiliary aircraft carriers were also well to the fore. As a result of these combined efforts the average of merchant vessel tonnage sunk for every U-boat lost fell swiftly from 40,000 to 6,000 tons. Well might the German Admiralty ruefully record that ‘the losses in May reached an impossible height’.

With German thoroughness they analysed the causes, and the table added to their War Diary is of particular interest. Thirty-five per cent. of the losses occurred when U-boats were approaching the operational area, and all were caused by aircraft. Within the operational area itself, the total losses were twenty-six per cent., ten per cent. being attributed directly to the air and thirteen per cent. to a combination of attack by aircraft and surface vessel. When in close contact with the convoy, the losses rose to thirty-eight per cent., of which twenty-two per cent. were caused by the escort vessels, ten per cent. by aircraft and six per cent. by a combined operation. The figures show the picture clearly enough. The farther away the U-boats were from the convoy, the higher the percentage of losses caused by aircraft. Only when the submarines came very close—in several instances appearing in the very midst of a convoy—were the escort vessels able to account for more of them than the aircraft escort. This was to be expected. To quote once more from the German Admiralty records: ‘The Royal Air Force played an

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important part in causing such high losses. This is to be attributed to the increased use of land-based aircraft and aircraft carriers combined with the possibility of surprise through radar location by day and night’. Such casualties were not to be borne.

At the beginning of May Dönitz was writing to his captains stressing the difficult position in which the U-boats were put by the fact that ‘the enemy is several lengths ahead of us in his radar location instruments’. He assured them that he would do everything he could to alter this situation, but that in the meantime they must pit their ‘ingenuity, ability and toughness against his (i.e. the enemy’s) tricks and technical developments’. They did so very resolutely, but, as has been seen, with no success. On 17th May Dönitz was forced to send message 1769 to all his captains. ‘The situation in the North Atlantic’, it read, ‘now forces a temporary shift of operations to areas less endangered by aircraft’. Thus by implication he admitted failure, and failure due to the persistent attentions of Coastal Command. The gallant skill of its crews and that of their American comrades could receive no better tribute. Dönitz had lost the bloody hard-fought round in the North Atlantic. He turned his attention to the south. So also did Slessor.

The Battle of the Bay, the assault that is, on U-boats making the passage to or from the Biscay ports, flared up in the early spring of 1943. It will be recalled that throughout 1941 and 1942 Air Vice-Marshal Bromet’s Group, No. 19, with its headquarters at Plymouth, and its squadrons disposed round the south-west shores of England and Wales, had been engaged in patrolling the grey waters of the Bay. The successes it had achieved had been limited and by the beginning of 1943 it had no more than the destruction of seven U-boats to its credit to which it was able to add two in the following month. In March of that year, however, there occurred an event which could be said to mark the opening of the decisive phase in this long drawn-out battle. The first ASV radar sets on the ten-centimetre band made their appearance and were installed in anti-submarine aircraft. The true significance of this device and its employment for the first time in that month must be appreciated. Not merely had a new and efficient mechanical means for the detection of U-boats been substituted for the old one-and-a-half metres ASV, which the Germans had been quick to counter with their search receivers, but the new instrument destroyed at a blow the immunity from detection which U-boats had, since October, 1942, enjoyed during the hours of darkness, and consequently the importance of the Leigh Light revived. As long as aircraft of Coastal Command were equipped only with an apparatus which the Germans could detect by a listening

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device and thus submerge before the aircraft fitted with Leigh Lights could close on them, the density of the patrols maintained by day was a matter of no significance. In daylight the U-boats merely ran submerged in order to escape visual detection and after sundown came to the surface to charge their batteries and to make use of their high surface cruising speed to escape from the danger area as soon as possible. Once, however, a machine had been devised and installed whose operations could not be detected by the enemy, the Leigh Light aircraft came into their own again, and throughout the twenty-four hours, including the five or six hours which the U-boat was compelled to spend on the surface in order to charge its batteries, their prey could be found and killed equally well by night or by day.

The main U-boat bases were at Lorient, St. Nazaire, La Pallice, Brest and Bordeaux. In pursuance of the decisions reached at the Casablanca Conference they had all been attacked by Bomber Command and some of them by the American Eighth Army Air Force. Lorient had received as much as 4,500 tons of bombs and St. Nazaire 2,000. The results appeared to be very disappointing and the Air Staff, which had not wished the attacks to be carried out, had the melancholy satisfaction of finding that they were in the right. ‘It is estimated’, wrote the Chief of the Air Staff on 26th March, ‘that the Lorient U-boats have lost the equivalent of three complete cruises and that, as a consequence, we have saved five or six merchant ships, or 50,000 to 60,000 tons of shipping’. This estimate was correct; no bomb had penetrated the roof of a submarine pen and none ever did so, though the roof of a pen in Brest was fractured sufficiently to let in daylight. The most that Harris and Eaker had been able to accomplish was the destruction of a number of servicing facilities. Such a result showed clearly enough that the bombardment of these submarine bases from the air was no short cut to victory.

The vital importance of the Bay was defined by Slessor in a memorandum submitted in April to the Anti-U-Boat Sub-Committee, and subsequently forwarded to the Combined Chiefs of Staff. ‘It is the trunk of the Atlantic U-boat menace’, he wrote, ‘the roots being in the Biscay ports and the branches spreading far and wide to the North Atlantic convoys, to the Caribbean, to the eastern seaboard of North America, and to the sea lanes where the faster merchant ships sail without escort’. It was obvious that the best way of felling this tree was by severing its trunk, that ‘little patch of water about 300 miles by 120 in the Bay of Biscay, through which five out of six U-boats operating in the Atlantic had to pass’. This area was within range of aircraft based in south-west England and on Gibraltar. Coastal Command was therefore set to patrol the ‘little

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patch’ in such a manner as ‘to give a reasonable certainty of sighting and hence a chance of killing every U-boat that passed through it’.

In instituting these patrols Slessor was adopting and amplifying tactics first used by the Royal Naval Air Service as far back as 1917, when ‘Spider Web ‘patrols had been flown with very considerable success over the North Sea. The effect was soon obvious. ‘The enemy guards the sea area of the Bay of Biscay’, reported Captain Mössel, the Naval Liaison Officer attached to the Luftwaffe, ‘in an extraordinarily careful manner. There are thirty to fifty aircraft above it a day’. The first success, that by an aircraft fitted with the new ten-centimetre ASV, occurred during operation ‘Enclose’, which began on 20th March. At 0059 hours on the 22nd, Leigh Light Wellington ‘G for George’ of No. 172 Squadron, Flying Officer P. H. Stembridge, Captain, sighted a U-boat in the act of crash diving and, attacking at once, dropped a stick of Mark XI Torpex depth charges. Almost immediately ‘two separate patches of very large bubbles were seen’. U-665 had met her end. This was the prelude to the sighting during that month of forty-two U-boats in the Bay. Twenty-four of them were attacked, sixteen between the 20th and 28th. It was fortunate that a period when the number of U-boats moving through the Bay into the Atlantic was increasing should have coincided with the moment when the new ASV equipment had restored the efficacy of the Leigh Light Wellingtons. No. 172 Squadron was able, on the average, to sight a U-boat once in every four sorties, a very satisfactory achievement, especially as in this early phase of the Battle the tactics of the U-boat commanders were usually to crash-dive on being sighted in the hope that they would be able to place a sufficient depth of water between their craft and the depth charges when they fell.

So far so good, but Headquarters, Coastal Command, were well aware that for every U-boat spotted two remained undetected and were able to submerge in safety. The next move, a change of tactics, came from the enemy. The U-boat commanders abandoned the crash-dive and stayed on the surface, there to fight it out with their anti-aircraft weapons, of which the number and calibre had been considerably increased. German submarines, their heavy guns removed, were now encountered mounting 37-mm. and 20-mm. anti-aircraft cannon and heavy machine-guns in the conning tower and sometimes fore and aft as well. With these they did not hesitate to engage aircraft which, in theory at least, presented an inviting target. The Liberator or Sunderland had to fly not only at a low height but also on a straight and level course if its depth charges were to be dropped with the necessary accuracy. Surely it was possible to shoot them down in the moments, brief though they were, when the run-in towards the

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U-boat was being made? Dönitz thought so, and urged these tactics upon his U-boat commanders. His view seems, at least in the beginning, to have been shared by Whitehall, where, noted Slessor,’ there were long faces ‘and prophets of gloom quick to point out how successfully our own trawlers, once they had been armed with Lewis guns, had dealt with the marauding Luftwaffe in the early days of the war.

The remedy, said the experts, was a new form of bombsight and a new form of bomb or depth charge which could be dropped from a height. The scientists should be called upon to design them as quickly as possible. These views were aired even in the Anti-U-Boat Sub-Committee, but met with no sympathy from Slessor. He had the greatest confidence in his crews who, he averred—and events were to prove him right—would not be deterred by casualties from attacking U-boats at a low level. The German submarine was, moreover, an uneasy anti-aircraft platform even in a calm sea. ‘It is up to us’, he wrote at the time in the Coastal Command Review, ‘to take the fullest advantage of the good opportunities offered before the buzz goes round in the Biscay ports that fighting back is an expensive and unprofitable pastime’. At the same time he did everything possible to give anti-submarine aircraft protection against anti-aircraft fire. Additional forward-firing guns were mounted and the gunners ordered to use them to the fullest possible extent during the run-up to the attack. The Australian Squadron, No. 10, based at Mount-batten, was the first to fit four additional .303 machine-guns in the noses of their Sunderlands, and other squadrons soon followed suit. With these the air gunners were presently able to engage with good effect at long range, and there is on record an attack on U.426 made on 8th January, 1944, by a Sunderland of No. 10 Squadron, in which the fire of its forward machine-guns, opened at 1,200 yards, killed or wounded all the German anti-aircraft gunners. After this the U-boat was destroyed ‘at leisure’.

During April, 1943, Coastal Command had little fortune. Out of fifty-two U-boats sighted in the Bay, twenty-eight were attacked, but only one sunk. In the following month, however, the number of U-boats sighted rose to ninety-eight, the number attacked to sixty-four, and the number destroyed to seven. It was becoming obvious that for the German submarine to stay on the surface and engage in battle with attacking aircraft was proving too costly, and while Dönitz was beseeching the Führer in the great room of the Berghof, with its incomparable view of sky and snow and mountain, for ‘an efficient radar interception set’ and proper facilities for neutralizing the effect of the ASV equipment, his captains were evolving yet a third form of tactics.

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In the first ten days of June, though our patrols continued to operate on an increasing scale, only seven U-boats were sighted. Had the battle been won already? For a moment it almost seemed that it had, when on the 12th the first of what was soon known as ‘group transits’ was discovered. On that day contact was made in the Bay with a formation of five U-boats outward bound. Here was a new development and its tactical advantages were obvious. One small group of which the units kept together was more likely to escape detection than three or four individual boats scattered over the patrol area. Fighter cover, mostly by Junkers 88C’s could be provided at the crucial spot and moment on a larger scale than before and the U-boats could give each other mutual fire cover. On being sighted they at once zigzagged and opened fire, which ‘was usually more determined and accurate than that of single boats’. This new method secured the enemy a temporary respite. The number of U-boats sighted in the Bay fell to fifty-seven and the number attacked to twenty-six. Only two were sunk by aircraft.

The attack of 13th/14th June by two aircraft of Coastal Command on U.564 well illustrates the hazards encountered when submarines cruising on the surface shewed fight. U.564 was attacked and damaged in the Bay by a Sunderland—‘U’ of 228 Squadron, Captain, Flying Officer L. B. Lee. The U-boat sent a signal to base reporting serious damage but claiming that the Sunderland had been shot down. The German Admiralty at once ordered another U-boat—U.185, which was in the neighbourhood, to go to the help of U.564. At the same time two German destroyers were ordered to sea from Le Verdon to meet and escort her home. Meanwhile at 1439 hours on the 14th a Whitley—‘G’ of No. 10 O.T.U. Squadron1—sighted two U-boats on the surface in 4417 north by 1025 west steering 075 degrees. Its captain, Sergeant A. J. Benson, asked for instructions. Base replied ‘carry out homing procedure for aircraft in the vicinity’. This involved shadowing the U-boats and summoning other aircraft with sufficient endurance to the spot. At 1757 hours whilst still pursuing a lone course ‘G’ of No. 10 O.T.U. Squadron signalled to base ‘have attacked with depth charges, hydraulics u/s’. After the attack and when struggling homeward the lone Whitley fell in with a number of Ju.88’s which had also been sent to the assistance of the U-boats. It was forced down and there were no survivors. Details of this attack did not come to hand until after the war; but according to

The Battle of the Atlantic 
(VI), June-August 1943

The Battle of the Atlantic (VI), June-August 1943


(i) By June 1943 carriers and very long range aircraft operating from Iceland and N. Ireland closed the N. Atlantic gap.

(ii) Very long range aircraft and carrier-borne aircraft also cover the S. Atlantic gap.

(iii) Consistent air cover off Brazilian coast.

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German records it was revealed that ‘during the afternoon of the 14th one British aircraft shadowed the two U-boats for some hours and finally attacked. Although repeatedly hit by both of the surfaced craft, the attack was pressed home on U.564 as a result of which she sank’. U.185 then picked up the survivors of U.564, met the destroyers as planned and resumed her outward passage.

It was at this point that the Admiralty were at last able to make available a surface hunting group to co-operate with Bromet’s aircraft. It was composed of the sloops Starling, Wren, Woodpecker, Kite, and Wild Goose under the command of Captain F. J. Walker, ‘that great U-boat hunter’, as Slessor calls him. For the next six weeks this force and the aircraft of Coastal Command wrought havoc among the U-boats. What happened on 30th July, when No. 502 Squadron and No. 461 Squadron RAAF and Walker’s sloops between them sank every one of a group of three U-boats in transit is vividly described by the Royal Air Force Liaison Officer on board HMS Woodpecker.

About 8.30 [he records] the fun really started. What a terrific day! A Sunderland and a Catalina were around and they signalled that no less than three U-boats were on the surface about ten miles away ahead. The Senior Naval Officer in Kite made the signal ‘General Chase’. Off we went at full speed, line abreast—a grand sight—smooth blue sea and blue sky—all ratings and officers at action stations. Soon we saw the aircraft circling low and diving to drop depth charges. Two of the U-boats were visible by this time and the Sunderland dropped a couple of depth charges plumb on either side of the conning tower of one of them. That broke the U-boat’s back and he disappeared pretty quickly, leaving some survivors and a raft in the water. Simultaneously, all our ships had opened fire with 4-inch on the second U-boat.2 He, too, left survivors who had to wait until U-boat No. 3 had been located and dealt with. Not unnaturally, No. 3 dived in some haste and we were now set the task of finding him beneath the surface. It was like great cats stalking an oversized mouse. Kite found him first and dropped a pattern of depth charges. Then Woodpecker set about him and dropped depth charges. Kite got a ‘fix’ and with his direction we proceeded to lay a ‘plaster’, which is rather what the name denotes. Wild Goose repeated the dose, but while she was doing so the first patches of oil were observed and soon it was coming up in great quantities—the sea stank of it. Wood and other wreckage came up too. This was about 3.30 p.m. We recovered various things. Wren found some German clothing. The evidence was decisive and the ships (which had been shielding one another during the action) reformed and made off to pick up survivors. We picked up seventeen, including the captain and 1st officer. The other ships picked up a further fifty or so altogether. Ours were in or clinging to a rubber float, shaped like a big rubber ring. Some were injured. One had a bullet in his stomach

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and a broken ankle. They were mostly shaking with cold and/or reaction from their experience. Several of them were truculent. Some had never been in a U-boat before—possibly never to sea before.

The sloops were able to collect more than a hundred prisoners from the U-boat victims of our air and sea forces. It was on this day that one of these strange coincidences, when fact far surpasses fiction, occurred—Sunderland ‘U for Uncle’ of No. 461 Squadron RAAF met and destroyed U.461.

A week passed and then the naval force returned, receiving as they reached Plymouth Hoe a signal of congratulation from the Commander-in-Chief, who took the salute as the leading ship passed by playing ‘A-hunting we will go ‘on her loud hailer. Such successes were gratifying and fully bore out the dictum that ‘the best U-boat killing machine is a really well trained and experienced team of air and surface craft’.

The joint pack hunted together until August when once more the enemy changed his tactics. The loss of four U-boats in the first two days of that month in the Bay of Biscay was evidently felt by him to be too severe. He abandoned, therefore, the attempt to traverse those waters on the surface and chose instead the safer method of hugging the north coast of Spain and moving as far as possible submerged. Walker’s sloops and Bromet’s aircraft at once followed the U-boats to the new area. Now, however, the British air and sea forces were far from their bases and close to those of the enemy. They were in fact almost within his grasp, for he, too, had not been idle and had a new weapon. On 25th August, the naval vessels watching the Spanish exit from the Bay were attacked by glider-bombs. One sloop was damaged. Two days later the enemy sank HMS Egret with heavy loss of life and severely damaged HM destroyer Athabaskan. In common prudence the surface vessels had to be withdrawn some two hundred miles to the westward out of easy range of German aircraft. Co-operation with Coastal Command suffered in consequence. Nevertheless, the patrols of the Navy’s vessels were continued until mid-September when information was received indicating that the U-boats were reappearing once more in the North Atlantic. This was a danger signal which could not be ignored, and the ships were therefore withdrawn from the Bay and sent farther north. Not until nearly a year later did they reappear in the Bay at a time when the rapid advance of Eisenhower’s forces south-westward from Normandy compelled German submarines to evacuate the Biscay ports.

Throughout the Battle of the Bay, Slessor and Bromet were constantly ringing the changes on their tactics. They were not so

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much altered as constantly varied. As early as March, 1943, the ‘Ribbon Offensive’ was instituted. Its object was to patrol ‘a ribbon of water of premeditated width athwart the transit route... night and day’. By so doing the airmen were given a reasonable chance of sighting, either by day or by night, every U-boat that crossed the ribbon, for it was calculated that each German submarine had to spend about five hours in twenty-four on the surface recharging its batteries. During this time it was cruising at ten knots, not at the three and a half which was its cruising speed during the other nineteen hours when it was submerged. The new patrols, known by the code-names of ‘Gondola’, ‘Enclose’, ‘Musketry’, and ‘Percussion’, were an improvement on the old ‘fan patrols’, and the peak of success was reached when in July eleven U-boats were sunk. This, Slessor was glad to note, ‘was a black month for the Axis’. Of 115 U-boats sighted during it, 88 were in transit through the Bay.

The aircraft engaged in this service had not infrequently to fight the Luftwaffe, whose long-range fighters made great efforts to protect submarines in transit. The adventures of Sunderland, ‘N for Nan’ of No. 461 Squadron, flown by Flight Lieutenant Walker, an Australian, on a June day in 1943 show how hard fought was the battle at that stage. On the 2nd, when well over the Bay at a height of 2,000 feet, eight Junkers 88’s were sighted six miles away on the port quarter. The Sunderland put on all possible speed and made for such clouds as were visible—they were very thin—but before it could reach them, the Junkers 88’s in hot pursuit had come within range. The crew, partly Royal Australian Air Force and partly Royal Air Force, jettisoned the depth charges and prepared to defend themselves. The Junkers peeled off in pairs. The first attack set the port outer engine of the Sunderland on fire, and an incendiary bullet ignited the alcohol in the compass. The fire in the engine was extinguished and the propeller feathered. A portable extinguisher quelled the fire in the compass which by then had set light to the captain’s clothing. On turning away one of the Junkers 88’s exposed its belly to the midship gunner who riddled it with bullets at point-blank range and sent it crashing into the sea. The next series of attacks inflicted further damage on the Sunderland. The hydraulics of the turrets were severed, the elevator and rudder trimming wires shot away, and the tail gunner was hit and fell unconscious over his guns. The nose and midship gunners, however, sent another Junkers 88 blazing into the sea, but the starboard galley gunner was mortally wounded. A third Junkers 88, coming in to the attack, was destroyed by the tail gunner who had regained consciousness, but

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by then—in the words of the Form Orange on which all actions were recorded—‘ conditions now became chaotic’. The radio had been shot away; the navigator was wounded in the leg and, since the inter-communication system had been severed, could only indicate the evasive action to be followed by hand signals. Nevertheless, the crew of ‘N for Nan’ continued to fly and fight their flying boat with the greatest coolness and resolution. Firing independently, the gunners set the port engine of a fourth Junkers 88 ablaze, and that was the end. Three Junkers 88’s had been destroyed, and almost certainly a fourth. ‘N for Nan’ was able to reach England, where its captain beached it. Every member of the crew on board was wounded, save one who was dead. The captain was admitted immediately to the Distinguished Service Order, and the navigator, Pilot Officer K. M. Simpson, awarded an immediate Distinguished Flying Cross.

The German fighters over the Bay were under the command of Fliegerführer Atlantik and belonged to the heavy fighter Gruppe of K.G.6, which had begun operations in September, 1942. During the winter, bad weather intervened and up to March, 1943, not more than twenty-seven of its aircraft had been sighted by Bromet’s fighters. The next three months, however, saw many combats in which the Luftwaffe lost on the whole more than it gained, so much so that at the urgent request of the local commander a number of Messerschmitt 110’s were transferred from Southern Italy to Brest. Here they operated in conjunction with the Junkers 88’s, but their successes were small in face of the Beaufighters and Mosquitos of Coastal and Fighter Command.

To interfere with our patrols at night, Fliegerführer Atlantik stationed nine night fighter Junkers 88’s at Nantes and called them the Kunkelkommando, after the name of their leader Hauptmann Kunkel. They did not prove very active and confined themselves very largely to shadowing. In February, 1944, a Staffel (about nine aircraft) of Focke-Wulf 190’s was formed, but these fine fighter aircraft, though they achieved some success, had too short a range. By then, too, the quality of the German pilots was beginning to deteriorate, and though some sixty twin-engined day fighters were available for operations and did, in fact, operate, it was soon observed that only the leader of the formation ‘showed knowledge of good fighter tactics’, the others making but timid and ineffectual efforts to close with their redoubtable opponents. All fighter protection for U-boats ceased with the dawn of ‘D Day’.

Throughout this period, that is from the autumn of 1942 to the early summer of 1944, the German fighters had been opposed by the

A ‘Kill’ in the Bay

Depth-charges from a 
Coastal Command Halifax straddle the U-boat

Depth-charges from a Coastal Command Halifax straddle the U-boat

The U-boat is engulfed in 
the plumes from the explosions

The U-boat is engulfed in the plumes from the explosions

The plumes subside, 
leaving 30 feet of the U-boat’s bow protruding vertically from the water

The plumes subside, leaving 30 feet of the U-boat’s bow protruding vertically from the water

Flying officer L

Flying officer L. A. Trigg, VC

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Beaufighters of Nos. 248, 143 and 235 Squadrons and by the Mosquitos of No. 10 Group, Fighter Command. As has been said, clashes were frequent and severe, and at one time in the summer of 1943 the average loss in Coastal Command was one aircraft a day. At the end of September, however, after the United States Eighth Army Air Force had bombed one of the main fighter bases, Kerlin Bastard—they also paid attention to the airfields at Mérignac and Cognac—the losses became smaller.

July was a black month for the Axis because for the first time, as Slessor noted, ‘we have come somewhere near the minimum numbers of aircraft for the Bay’. He had achieved this most desirable, indeed essential, concentration by reinforcing Bromet’s Group at the expense of other Groups and thus increasing the total number of aircraft available for the Bay offensive by forty. Moreover, the two American Army squadrons were just arriving. By the end of August, yet another change of tactics on the part of the U-boats in the Bay once more reduced their losses. The fighting back tactics were abandoned and the German submarines moved all day submerged, only coming to the surface at night for the minimum time necessary to charge batteries. This return to an earlier method of escaping detection was the salient feature of the fourth and last stage of the Battle of the Bay. Slessor did his best to counter it by increasing as far as possible the night patrols by the Leigh Light Wellingtons and by re-equipping and re-training No. 304, a Polish Squadron. He also tried, though not very successfully, to induce the heavily-burdened aircraft industry to hasten the production of Leigh Light equipment for the Liberators. ‘Percussion’ patrols were intensified, since it seemed certain that U-boats continued to find their way into the Atlantic by hugging the coast of Spain.

The Mark III ten-centimetre ASV was still working undetected and the enemy had not been able to produce either a search receiver on the centimetre band or any effective radar warning gear. As early as 31st May, 1943, Dönitz was demanding as a matter of the utmost urgency an efficient radar interception set able to show the frequency used by the radar-equipped aircraft. At that time, he was complaining bitterly that ‘we do not even know on what wave-length the enemy locates us; neither do we know whether high frequency or other location devices are being employed’. The immediate remedy, a desperate one, had been to order the U-boats to move only at night when they were to run on only one electric motor. Several unsuccessful devices were tried. Small balloons, from which strips of metallic ribbon were suspended, were released by U-boats during their transit through the Bay, the object being to confuse the ASV operator in

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the searching aircraft. Their code-name was APHRODITE, the Goddess of Love, but neither she nor THETIS, daughter of a Sea-God, the code-name for spar-buoys supporting similar reflecting material, proved of much value. The coating of U-boats hulls with rubber against ‘Asdic’ detection was also attempted and the conning towers were sprayed with a special paint thought to be effective against infra-red rays. Since we were not using them, this paint served no useful purpose.

The original search receiver fitted in U-boats had been evolved as the result of the capture by the enemy of a Hudson in March, 1942, equipped with the 1½-metre Mark II ASV. The counter-device for this was first produced by the French firm of Metox and was known as Metox 600. It had a range of about forty miles and would thus in theory give ample warning of the approach of aircraft, so that the U-boat would have time to submerge before being sighted. Metox worked well until the beginning of 1943 when, as has been related, Coastal Command changed its ASV equipment for the ten-centimetre apparatus against which Metox was ineffective. In March, 1943, however, just a year after the Hudson with the ASV Mark II had fallen into his hands, the enemy had the good fortune to shoot down an aircraft of Bomber Command fitted with ten-centimetre H2S, the special navigational equipment then coming into use based on the same principle as the ten-centimetre ASV. The consequences might have been serious, but it was not until September that the full significance of this equipment, as applied to U-boat detection, was realised. The Germans at once set to work and produced a counter-device, but by then the fitting of Schnorkel tubes to U-boats had begun and it was therefore largely superfluous.

It was maintained in theory that whatever apparatus the enemy might use would prove of no avail if the principle known as ‘flooding’ could be put into practice. The scientists of Coastal Command urged that the area under patrol should be so flooded with continuous ASV signals emitted during the hours of darkness as to bring the U-boat captains face to face with two alternatives, both equally unpleasant. Either they would have to keep boats submerged at night and would, therefore, have to spend four or five hours of the following day on the surface recharging batteries, thus providing a reasonably easy mark for the day patrols, or else they would have to ignore the numerous signals picked up by their detecting apparatus, remain on the surface at night and make for the Atlantic at their best speed. If they followed this plan, they ran grave risk of discovery by a Leigh Light aircraft. That was the theory; but its practice was impossible for it demanded very large numbers of aircraft, all

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equipped, of course, with the ASV Mark III, and this instrument could not be produced in sufficient quantity quickly enough to satisfy the requirements of both Coastal and Bomber Command, where it was known as H2S. When these difficulties were overcome, its allocation to No. 8 Group of Bomber Command (Pathfinder), was considered at this stage of the war to be of overriding importance.

By the end of August, 1943, not only were the casualties caused to U-boats far above the highest wastage rate acceptable to the enemy—fifty-six U-boats were lost in the Bay and in the North Atlantic between 1st June and 1st September—but the nerves of their crews, brave though the great majority were, were near breaking point. ‘The Commanding Officer’, says the telegraphist of U.523 sunk on 25th August, ‘was continually on my tail telling me to report immediately the slightest contact. His nerves communicated themselves to the entire crew. We had had a shake-up before. As we left our base we were impressed by the sight of another U-boat arriving in a practically sinking condition after aircraft attack’.

‘We felt as if we were being led to the slaughter house’, said the Chief Petty Officer of U.135 describing his feelings when facing his sixth passage through the Bay. ‘You’ve no idea how unnerving is the effect of repeated alarms’, observed a prisoner from U.202. ‘The loudspeaker begins to sound like the voice of doom’. But perhaps the most significant remark of all was that made by an officer from U.506, sunk on 12th July in the North Atlantic. ‘It’s no longer any fun’, he said, ‘to sail in a U-boat. We don’t really mind even a cruiser, and we can face destroyers without turning a hair. But if an aircraft is there, we’ve had it. It directs surface craft to the spot even if it does not attack itself’. These remarks came from the lips of shaken prisoners, but, even after due allowance has been made for their condition of mind, it was obvious that by August, 1943, the situation from the German point of view was very serious. Nevertheless, the enemy still continued the struggle, but for the moment his U-boats may be left edging their way precariously out of the Bay, under constant threat of attack, while the fortunes of such of them as made the passage to the Atlantic are once more considered.

It will be recalled that by May, 1943, Dönitz had ordered his U-boats to quit the North Atlantic because of the heavy losses they had there sustained. The shifting of the focus to the Bay of Biscay merely shifted the position of the graveyard, and by 7th August, Dönitz was facing a grim butcher’s bill; for three months past an average of thirty U-boats had been sunk a month, and the Allied shipping losses had been reduced ‘to a relatively negligible quantity’.

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Nevertheless, he did not despair. His new weapon and a new safety device were, he knew, almost ready. All might yet be regained. The new weapon was the acoustic torpedo; the new device, the Schnorkel breathing tube. The Schnorkel consisted of two tubes fastened together and hinged to the deck of the submarine, usually just forward of the port side of the bridge. When erected, one end of the tube was level with the top of the periscope when fully extended. Its bore was fourteen inches, and it was covered by a cowl containing an automatic valve designed to prevent the entrance of sea water. The exhaust tube immediately abaft the breathing tube was five feet shorter, and its top was therefore just below the surface of the water. When a U-boat wished to charge her batteries with the aid of the Schnorkel tube, she was brought to periscope depth and moved ahead on her engines, dead slow. The Schnorkel was raised, and the valves connecting it to the normal air intake and to the exhaust pipe of the Diesels opened. The U-boat was then driven by the Diesels which, at the same time, charged her batteries. It was soon found that in the Atlantic she could move at a maximum speed of between five and seven knots. The advantage of this device was obvious; instead of displaying the whole of her superstructure when charging her batteries, the U-boat now showed only a few feet of inconspicuous tubing. The disadvantages, however, were great. If the air intake valve, for example, were shut by the impact of a wave, the engines had to be stopped immediately, but even so the air pressure inside the boat dropped violently, thus causing acute discomfort. Careful trimming could mitigate, but not eliminate, this difficulty; the stopping and starting of the engines, resulting in very serious variations in the air pressure, made physical conditions in the submarine so bad that the crew might be, and often were, reduced to a condition of extreme physical and mental depression. For this reason alone the Schnorkel was not popular at first, despite the greatly increased protection it gave to the U-boat when charging her batteries, and the fact that it was very difficult, if not impossible, to detect by means of ASV.

The acoustic torpedo was an ingenious weapon which, when fired, homed on the noise made by a ship’s propellers. As soon as its listening apparatus picked this up, it altered course and made straight for this most vital spot.

Such weapons, however, were not enough. The German High Command realised that to achieve mastery a new type of U-boat was necessary. It therefore ceased the production of the conventional model and turned to a new model, the prefabricated types XXI and XXIII. These were of novel design and high speed. Type XXI, with a

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displacement of some 1,600 tons, had a range of 19,000 miles on the surface at a speed of six knots and could at a pinch move at sixteen knots submerged, though only for a distance not exceeding twenty-five miles. She carried twenty torpedoes and had a complement of fifty-seven. Type XXIII was a much smaller vessel of some 230 tons displacement, capable of a submerged speed of ten knots for a distance of forty-three miles. Her complement was fourteen and she carried two torpedoes only. To cover the period between their design and their appearance in the ocean the Schnorkel tube had been developed and it was hastily fitted to the conventional type of U-boat in the hope that it would afford it sufficient protection to enable the fight to be carried on until the new models were ready.

The Schnorkel tube was not yet in operational use when Dönitz made another strong effort to regain Germany’s position in the North Atlantic. He sent his U-boats once more into that ocean to patrol in groups of from fifteen to twenty on a line running north and south. The individual units of each group, to which a separate code-name was given, were ordered to form a patrol line some 285 miles long, each unit being separated from the next by about fifteen miles. The patrol line was then manoeuvred north, south, east or west so as to stretch it across the path of a convoy. The key to success lay in the accurate reporting of the first contact with the convoy so that the remaining units of the group would be able to converge upon their prey. If the sighting U-boat made the report too late, then the convoy had time to slip through the gap between two boats and move out of reach of the pack before its members had had time to converge.

What happened to convoy ON.204 well illustrates the difficulties under which the U-boats worked. On 4th October, the first boat of the patrol line formed by Group Rossbach reported at 0700 hours that she had been hunted at 1645 hours on the 3rd. She repeated this message at 1035 hours on the 4th, but in the meantime the Rossbach units had been ordered to close to meet the convoy. They made towards it all that day and at 1700 hours the captain of U.336 reported that he had seen aircraft to the westward and added, almost casually it would seem, that at 2100 hours on the previous day he had caught sight of a destroyer. It will be noted that he had allowed some twenty hours to elapse before informing the German Admiralty of this very important sighting. They quite rightly concluded that the destroyer in question formed part of the escort of ON.204 and, therefore, that the convoy must have slipped through the line. This indeed had proved to be so and they were not unnaturally much put out. A curt note in their operational diary says: ‘Why this

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extremely important report from U.336 was not made immediately will have to be explained by the commanding officer when he returns’. The explanation was never given, for U.336 with its delinquent commander encountered the United States Ventura ‘B’ of the 128th Squadron and was sunk with all hands.

Such was the general manner in which the U-boats operated at this time. By the middle of September a number of them had been able to elude our patrols and a pack of about fifteen, armed with acoustic torpedoes, was in the North Atlantic lying in wait for a prey. Their opportunity arrived when two Allied convoys, ON.202 and ONS.18, amounting in all to sixty-eight vessels, were about ninety miles from each other moving on a converging course. They were some 650 miles outward bound from England, and still under the protection of the very long-range Liberators of No. 120 Squadron based on Iceland. The attacks on both convoys began at dawn on 20th September when one of the escorting vessels was torpedoed and lost her stern, including her propellers and rudder. She was ultimately towed to the United Kingdom. The next victims were two merchant vessels, and thereafter the attacks developed on a considerable scale. About noon, ON.202 and ONS.18 were instructed to join company so that their escorts might act in concert. The manoeuvre was more easily ordered than accomplished. ‘The two convoys’, reported Commander M. J. Evans, the Senior Officer of the combined escort in HMS Keppel, ‘gyrated majestically round the ocean, never appearing to get much closer and watched appreciatively by a growing swarm of U-boats’. By darkness, however, the operation had been completed with the loss of the Canadian St. Croix, and the corvette Polyanthus. The night of 20th/21st September passed quickly, and there was thick fog the next day which prevented any serious attack. By that evening there were indications that the U-boats were again massing. They began their attacks at 2100 hours and continued them until 0600 hours on 22nd September but without any effective result. The next day, too, was foggy until the evening, when, on the weather clearing, Liberators of No. 10 Squadron of the Royal Canadian Air Force appeared from Newfoundland. The crew of one of them, ‘L for Love’ spotted a U-boat on the surface about sunset and at once went into the attack. The German gunners offered stout resistance, put a bullet in the crank-case of one engine, and with another ‘parted the hair above the navigator’s left eye’. The Liberator’s depth charges were accurately dropped, but the U-boat still remained on the surface. ‘L for Love’ signalled for help, but none could be given, for the surface escort was fully engaged and the only other aircraft in the neighbourhood replied from forty

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miles away, ‘Have a U-boat of my own’. This aircraft, ‘X for X-Ray’, had just dropped four depth charges on it, and was about to drop four more. Having done so, it then engaged the U-boat with machine-gun fire but without definite results. The battle continued through the 23rd and 24th September. In all, six merchant ships and three escorting ships were sunk, four of them by acoustic torpedoes. The enemy lost three U-boats—one of which was sunk by No. 120 Squadron and another by No. 10 Squadron RCAF.

The Germans’ next attempt to regain the initiative took place in the first fortnight of October, when possibly the same U-boat pack was foolish enough to select a hunting ground within easy reach of Iceland. The result was disaster. On the 4th it lost two U-boats, one to a United States Squadron, the other to Liberator ‘X for X-Ray’ of No. 120 Squadron, Royal Air Force. On the next day it lost one to a Hudson of No. 269 Squadron and one to a Sunderland, ‘J for Johnnie’ of No. 423 Squadron of the Royal Canadian Air Force. It lost one more on the 13th and then on the 16th and 17th came the climax. On the 16th four U-boats were sunk, all by Liberators of Nos. 86 and 59 Squadrons, and on the 17th, three—one by the indefatigable Liberators, and two by the Navy. Before the month was out seven more had been sunk in the North Atlantic, bringing the total for the month of October in that one area alone to twenty. No navy could stand such losses. And to them must be added two more U-boats sunk in the area of the Azores, which had by then become an Allied base under Bromet.

‘It must always be one of the mysteries of the war’, says Slessor, ‘that the enemy should have waited (in 1943) to stage a serious attack on the Gibraltar convoys until we were established in the Azores and were thus in a position to give them effective air cover throughout their passage’. Be that as it may, in the middle of November, 1943, when Bromet’s force was well established on the island of Terceira (he had been succeeded at No. 19 Group by Air Vice-Marshal B. E. Baker), a large pack of U-boats assembled in that area with the evident intention of attacking convoys SL.139 and MKS.30. At one moment it seemed as though a major battle would take place, for, in addition to the U-boats, the enemy also made use of long-range aircraft, among them being Heinkel 177’s, Junkers 290’s and Focke-Wulf 200’s, which the Fliegerführer Atlantik had by then received as much-needed reinforcements. They were armed with radio-controlled bombs with which they succeeded in sinking one ship and damaging another. Though these aircraft were successful in discovering and attacking these convoys, ‘the U-boats’, complained the melancholy Mossel, ‘are so greatly hindered in their

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attacks by enemy aircraft that hopes once cherished cannot be fulfilled. Until we can do away with the enemy’s strong air threat to our boats, our successes will be few and far between’. Their captains lurking uneasily beneath the Atlantic swell were evidently of the same opinion. No attempt was made to follow the convoys by day, nor was there any inclination to join battle.

The year closed, then, with the Allies in high fettle on all the seven seas. The average monthly losses of merchant shipping had fallen from slightly over 520,000 tons in 1942 to about 130,000 tons in the last six months of 1943.

The pilots and crews of the aircraft, though they played the main part, were not alone responsible for the victory. To the planners and the ground staff much credit is also due. Men like Professor A. C. Gordon, Air Commodore I. T. Lloyd, and Air Commodore T. A. Warne-Browne, laboured without pause to increase operational efficiency by rationalising the system of servicing and maintaining the aircraft belonging to the various squadrons. The object of what came to be known as ‘Planned Flying and Maintenance ‘was to extract’ the last ounce of operational effort per maintenance man-hour out of the aircraft available’. An experiment in planned flying and maintenance had been made in August, 1942, when Sir Philip Joubert was Commander-in-Chief, and by February, 1943, many squadrons were practising it. The object was to reduce as far as possible demands for the reinforcement of Coastal Command. Slessor was well aware that to build up the offensive strength of Bomber Command was the real crux of the problem of air warfare. Coastal Command was essentially a defensive organization and should therefore draw as little as possible on limited resources which should be devoted to the offensive. By the skilful husbanding of his aircraft, he believed that he could not only prevent wastage but actually increase efficiency. He was right and the means he chose, ‘Planned Flying and Maintenance’, were soon seen to be more than adequate. The squadrons undergoing it were divided into three general categories each with a different form of maintenance establishment. Category one were those required to operate regularly and as a matter of routine; in category two were those squadrons used as and when occasion offered and whose efforts were therefore spasmodic and variable—in this category, for example, came convoy escorts; category three was made up of aircraft detailed to seize fleeting opportunities and called upon, therefore, to make the maximum possible effort on sudden but relatively rare occasions. The Strike squadrons against shipping formed part of these. Maintenance staffs were reorganized into daily servicing sections and

The battle of the Atlantic 
(VII), September 1943–April 1944

The battle of the Atlantic (VII), September 1943–April 1944

Note (i) The central Atlantic gap closed by very long range aircraft from the Azores and by carrier-borne aircraft.

(ii) Air support to Russian convoys supplied by British carrier-borne aircraft, March—April 1944

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repair and inspection sections were centralized into a servicing Wing commanded by the Chief Technical Officer on the station. It was his duty to produce by means of rationalization serviceable aircraft in sufficient numbers to fulfil any task which might be laid upon the squadrons flying them. Such a system depended on the keeping of accurate statistics by Headquarters, Coastal Command, and on the accurate daily submission by all stations of returns shewing the ‘state’ both of aircraft and maintenance staff. The introduction of this system, though admittedly somewhat soulless and smacking of the factory rather than of the battlefield, increased the ratio of operational flying hours to maintenance man-hours by between thirty and forty per cent., and thus very materially contributed to winning the Battles of the Bay and of the Atlantic.

Another equally important factor in the victories achieved was training. In 1943, Coastal Command succeeded in training 1,233 crews for overseas commands and 640 for home commands. This was reasonably satisfactory and was a continuation of the policy pursued by Air Marshals Bowhill and Joubert. However good might be the work performed in the operational training units, the final hallmark of a successful and efficient crew was conferred by the battle itself. The old principle, an ounce of practice is worth a ton of theory, was demonstrated again and again. The destruction of U-boat U.304 by a Liberator, ‘E for Edward’ of No. 120 Squadron, Royal Air Force, provides a typical example of the skill acquired by experience. The aircraft, piloted by Flight Lieutenant Fleming-Williams, was due to protect convoy HX.240 crossing the Atlantic from the United States of America to Britain. On his way to meet it he flew through unexpected and very bad weather for about four hours, and had just emerged when he sighted a submarine five miles away at the very limit of his visibility. There was a 35-knot wind blowing, the sea was very rough and covered with white caps, and it was the irregularity in their pattern which first excited the pilot’s attention. His practised eye had not deceived him. The flurry of foam in the midst of the wind-lashed sea was caused by a submarine fully surfaced. Fleming-Williams immediately turned away so ‘as to give the submarine commander the feeling that I had not seen him’. He made for a cloud, and taking cover in it emerged much closer to the U-boat. Her captain began to dive, but Fleming-Williams, bringing his Liberator down to 100 feet, dropped four depth charges. They fell along the port side of the submarine, which was immediately hidden by vast sheets of spray. These dissipating, ‘I saw a big cylindrical object which I took to be a torpedo tube that had come adrift’. The depth charges had been accurately placed, due allowance

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having been made for the strong wind on the starboard quarter. U.304 had been destroyed.

In one commodity the Command was never lacking—courage. The gloomy prognostications of those who maintained that, when the U-boats decided to stay on the surface and fight it out, the rate of casualties would rise too sharply to be bearable, never came even within sight of fulfilment. Whatever the conditions, fog and mist and low cloud or bright sun and dancing waves, the Sunderland or the Catalina or the Liberator on sighting a U-boat on the surface went resolutely into the attack regardless of the possible consequence. It was in one of these encounters which, though not directly connected with the Battle of the Bay, is typical of many such, that Flying Officer L. A. Trigg, of New Zealand, earned a posthumous Victoria Cross on evidence furnished by the enemy. On 11th August, 1943, when flying Liberator ‘D for Dog’ of No. 200 Squadron on anti-submarine patrol off the coast of West Africa, he sighted U.468 some 240 miles south-west of Dakar. She was on the surface and made ready to defend herself. The shooting of her anti-aircraft guns was heavy and accurate. ‘D for Dog’ was hit repeatedly and arrived in a position to attack, on fire in several places. Nevertheless, the depth charges were dropped and within twenty minutes the U-boat was on the way to the bottom. By then ‘D for Dog’ had struck the sea a wreck, and all her gallant crew perished with her. One of her dinghies, however, released by the impact, floated clear and served as a means of safety for some of the U-boat’s crew, whose evidence was subsequently accepted when making the posthumous award.

On 20th January, 1944, Air Chief Marshal Sir Sholto Douglas took over Coastal Command from Slessor, who was appointed Deputy Allied Air Commander in the Mediterranean theatre and C.-in-C. of the RAF in the Mediterranean and Middle East. It was soon evident that the U-boats, of which there were still some sixty at sea, had abandoned the tactics of the pack for individual patrols. This made them much harder to find and destroy, but they could do very little harm to convoys. Not until April, 1944, were they brought back into the Biscay ports, there to wait until an opportunity should arise to use them against the Allied invasion, which the enemy believed by then to be imminent.

Not all the U-boats were operating individually. Some had been collected in small packs and were confining their operations mostly

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to the western seaboards of Scotland and Ireland. In these waters they remained submerged by day and searched them only by night until forced to dive by the presence of aircraft. To meet these new tactics Sholto Douglas reduced the number of patrols in the area of the Bay of Biscay and increased the concentration of his force on the western seaboard. Air Vice-Marshal Slatter of No. 15 Group, responsible for the air/sea war in that area together with Admiral Max Horton of Western Approaches, was given the co-operation of Nos. 18 and 19 Groups, and also of the squadrons based in Iceland. Thus ‘a well-coordinated offensive was maintained with relative economy in the employment of aircraft, and the combined air and surface patrols brought a weight of attack upon the U-boats sufficient to force them further out into the Atlantic’.

Admission to the Mediterranean was denied by Leigh Light squadrons based on Gibraltar, but as ‘D Day’ approached, these were gradually withdrawn and the defences of the gateway to that sea were left to a much reduced force under Air Vice-Marshal Elliot and to the American squadrons of the Moroccan Sea Frontier Force based on Lyautey.

The enemy’s new tactics of remaining submerged by day increased the importance of night operations. To convert a contact obtained by radar into the sighting of a U-boat demanded great accuracy on the part of the radar operator. Training in the manipulation of the Leigh Light was therefore intensified, the object being to make as many squadrons as efficient as possible before the advent of ‘D Day’ provoked the enemy to a renewal of his attacks. In the meantime, Mosquitos fitted with a six-pounder gun began to operate over the swept channels to the enemy’s Biscay bases and achieved a certain degree of success, two Mosquitos of No. 248 Squadron sinking, on 25th March, a U-boat in a position much closer to the French coast than ever before.

All these measures can be described as of a routine nature. The main problem from the beginning of the year onwards was how best to use the 430 odd aircraft of Coastal Command available for the protection of the navy and the army on ‘D Day’. It was thought highly probable that, as soon as the invasion was launched, the U-boat fleet would make a determined attempt to cut all communications by sea between France and England and that in this it would be assisted by light forces of destroyers, torpedo boats and E-boats. Such a view became virtually a certainty when a marked reduction

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of the number of U-boats at sea during March was observed. This was, in fact, due not only to the necessity of fitting them with new devices, but also to the German High Command’s suspicion that the day of invasion was approaching. They had decided to hold back as many U-boats as they could in order to use them with what they hoped would be decisive effect when the moment came. Coastal Command’s main and most obvious counter-measure was to deliver attacks by day and night on all enemy U-boats in the south-western approaches to the English Channel, and to combine these with attacks by the anti-shipping squadrons upon the enemy’s surface craft.

The tactics were planned at a series of conferences between the responsible authorities, including the leaders of the Expeditionary Force. The enemy might make use of 130 U-boats if he were to draw on those in Norwegian ports and in the Baltic. These he was expected to reinforce with a further 70 within a fortnight of ‘D Day’. In point of fact Dönitz drew only on the thirty-six in the Biscay ports. To render their manoeuvres of no avail, Coastal Command was to maintain a day and night patrol over the western end of the English Channel, and the number of aircraft carrying it out was to be large enough to make certain that no U-boat would be able to move to the battle area on the surface. It would have to pass through the area covered by the patrols wholly and continuously submerged. The distance to be traversed in this fashion would, however, be so great that such a feat would be almost impossible. At some point and at some moment the U-boat would have to come up for air and then it would be immediately attacked. Even if by a great feat of endurance a few succeeded in slipping through, their crews, it was thought, would be so exhausted as to be an easy prey to the escort vessels of the invasion convoys.

Patrols of a similar kind, though less dense, would also be mounted in the eastern approaches to the Channel and these, together with the maintenance of attacks in the northern U-boat transit area between Norway and Iceland would, it was hoped, be sufficient to deal with the menace of the submarine.

In April, 1944, Sholto Douglas issued a directive setting out clearly the role of his Command. No. 19 Group, based on Plymouth, was to provide the patrols in the south-west approaches of the Channel and to escort convoys. No. 16 Group, at Chatham, was to perform a similar office in the event of an attempt by German U-boats to attack from the north and enter the northerly approaches of the Channel. No. 15 Group, based at Liverpool, was to continue to cover convoys in the Atlantic and to attend to the northern transit

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area; in this they were to be assisted by No. 18 Group based at Rosyth. Such were the plans, and those who made them were presently making great use of the simile of the cork in the bottle. The bottle was the southwest approaches to the Channel where the main U-boat attack was expected; the cork was the dense series of patrols which was to be established over areas in those approaches chosen in such a way as to take the fullest advantage of the flexibility of the air weapon. What happened will be recounted later. The other activities of Coastal Command in 1943 must now be considered.