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Chapter 5: The Opening Phase, (September 1939–May 1940)


DURING the first week of war the ten Battle squadrons of the Advanced Air Striking Force and the four Hurricane squadrons allotted to the Air Component crossed the Channel without interference from the enemy. They were followed by the eight reconnaissance squadrons of the Air Component, the first of which reached France about the middle of September. By the fourth week in October the Dover mine barrage at the southern exit from the North Sea had been completed. Meanwhile the four divisions of the Expeditionary Force had taken up the positions assigned to them.

The departure of the Expeditionary Force left the United Kingdom guarded on land by weak forces under Western, Southern, Eastern, Northern and Scottish Commands, the whole responsible to General Sir Walter Kirke, Commander-in-Chief, Home Forces.* At the outset of the war invasion was not expected, and the main task envisaged for General Kirke and his subordinates was to prepare drafts for despatch abroad while absorbing the flow of recruits created by conscription. As we have seen in the last chapter, the air defences were considerably below their planned strength, but British naval forces in home waters far outmatched the small surface power of the German navy.

In the spring of 1939 the Air Staff had put the size of the German long-range bomber force at 1,650 aircraft and the possible weight of attack during the first two weeks of war at 700 tons a day.1 The true position was not quite so alarming. On the outbreak of war the Germans had 1,180 long-range bombers, of which 1,008 were serviceable, besides about 400 short-range dive-bombers and ground-attack aircraft. Their total first-line strength, including transport machines, amounted to some 4,000 aircraft.†2 Unlike our own, their fighter force of roughly 1,200 aircraft was intended more for tactical support of an army in the field than for home defence. For the latter purpose they

* Aldershot Command, also under C.-in-C. Home Forces, was responsible for providing drafts and reserve formations.

† See footnote * on page 78.

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relied mainly on a plentiful supply of guns. Reserves, which were estimated in London at five times the true figure, amounted to fewer than a thousand machines fit for the first line, while production, at roughly seven hundred aircraft a month, was almost the same as the British for a first line twice as great as ours. The training organisation commanded some 3,000 aircraft, of which about 500 were of first-line type. On the other side of the account, the British and French metropolitan air forces mustered between them about 3,400 first-line aircraft and nominally about 3,800 aircraft in reserve.†3 On the whole, the Allied organisation was far less suited than the German to support a land campaign, while both the first line and reserves included many machines whose performance was not up to modern standards. Figures apart, events soon showed that effectively the Luftwaffe was substantially stronger than the British and French air forces put together.

Shortly before the war the British Air Staff had come to the conclusion that the enemy was unlikely to begin by bombing individual factories or arsenals.4 More probably he would seek to destroy the nation’s will to fight by attacking densely populated areas or vital links

* The precise figures were:

Strength Serviceable Aircraft
Long-range bombers 1,180 1,008
Dive-bombers 366 318
Ground Attack Aircraft 40 37
Fighters (all categories) 1,179 1,053
Long-range reconnaissance (excluding Coastal) aircraft 262 235
Short-range reconnaissance aircraft 342 294
Coastal aircraft 240 214
3,609 3,159
Transport aircraft 552 540
4,161 3,699

† According to a statement made to the War Cabinet by the Secretary of State for Air, the figures on 26th September were:

British French
First Line Reserves First Line Reserves
Bombers (all categories) 536 1,450 463
Fighters (all categories) 608 320 634
Long-range reconnaissance (excluding Coastal) aircraft 444
Short-range reconnaissance aircraft 96 105
Coastal aircraft 216 125 194
Fleet Air Arm 204 200
1,660 2,200 1,735 1,600
OVERSEAS All types 415 595
2,075 2,330

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in the system of supply and distribution. London seemed a likely target, since it was at the same time a great port, an important residential centre and a focus of commerce, industry and government. Other promising objectives included the industrial districts of Lancashire and the Midlands, and the chief ports outside London, from the Forth to the Mersey and Belfast.

In Poland, however, the Germans opened their attack by striking at the opposing air force and its bases. Other campaigns might begin in the same way. The Royal Air Force, protected as it was by an unrivalled early-warning system and a well-planned system of dispersal, could reasonably hope to escape destruction on the ground, but might be gravely injured by damage to the factories on which it counted for supplies.

Accordingly reports from Poland soon led the Air Staff to modify their estimate of the enemy’s most likely course of action. A fortnight after the declaration of war, Air Chief Marshal Dowding was directed to review the deployment of the air defences on the assumption that ‘the aircraft industry is to be regarded as a very probable first objective for enemy air attacks against this country’, and to pay special attention to Sheffield, Coventry, Derby and Bristol, where there were factories of great importance to the air force.5 As attacks on London could not be ruled out, these orders looked like a clear instruction to the Commander-in-Chief to apply himself to the defence of London, the industrial Midlands and Bristol, even at the expense of other tasks. In reality much else had to be considered. As we shall see in later chapters, many additional demands were afterwards made on the air defences, and were often urged with much force and authority. At no time during his tenure of office was Dowding able to get from the Air Staff a clear statement of their relative importance; and admittedly such an assessment would have been extraordinarily hard to make.

In the outcome the German assault was postponed for the best part of a year, and was then directed to ends which differed considerably from those foreseen in 1939. At the beginning of September nearly half the Luftwaffe, with the better part of the German army, was on the Polish front.6 There is no evidence that the German High Command had sanctioned even provisional plans to use the other half against this country.7 As no invasion of the United Kingdom was in view, an attack on London would not have been consistent with an outlook which sought to justify the bombing of Warsaw on the ground that it paved the way for military occupation of the city. Moreover the German Government did not favour measures calculated to destroy the hope of a peaceful settlement with Great Britain when Poland was defeated. Thus the ‘knock-out blow’, round which so much British planning had revolved, was not attempted. Some weeks

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after the outbreak of war the Intelligence Division of the Operations Staff at the German Air Ministry did, indeed, urge that British ports should be vigorously attacked; but they made no mention of inland cities. Ultimately even their plea for a strictly limited programme of strategic bombing was rejected.


On the other hand, attacks on shipping by German naval and air forces began at once.

Until 1939 the Air Ministry in Berlin, like its counterpart in London, had done little to provide a striking force expressly trained for maritime war. In the spring and summer of that year its attention was drawn to the possibility of using bombers against British warships in harbour or at sea.8 The outcome was a small anti-shipping force commanded by General Hans Ferdinand Geisler, a former pilot of the naval air service who had joined the Luftwaffe in 1933.

After the outbreak of war Geisler’s task was widened to include attacks on merchant ships and naval auxiliaries. Occasionally harmless fishing-vessels were attacked, perhaps because they were mistaken for minesweepers. As a trawler screen was posted off the East Coast while the C.H.L. stations were lacking, they may alternatively have been suspected of reporting German movements. Less understandably, attacks were sometimes made on lightships, which admittedly helped Allied shipping but were also useful to the Germans. On 9th September Geisler’s force, which included some of the newest bombers and best crews in the Luftwaffe, numbered 85 aircraft, of which 71 were fit for active service.*9

German naval dispositions for war on merchant shipping were put in hand some days before the outbreak of hostilities. Between 19th and 29th August seventeen ocean-going submarines out of a force of twenty-six left Kiel for the Atlantic, while fourteen short-range submarines out of thirty made their way to the North Sea and the English Channel. By the end of the month thirty-nine German submarines of all classes were at sea.10 As soon as the Allied ultimatum gave the signal they struck at the supply lines which finked Britain with the outside world. Their commanders had orders to observe the international convention which forbade the sinking of merchant

* It comprised:

Unit Equipment Strength Serviceable Aircraft
Kampfgeschwader 26 Heinkel 111 65 58
I/Kampfgeschwader 30 Junkers 88 20 13

The Junkers 88 was the newest German bomber, and I/KG. 30 was the first unit equipped with it.

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vessels without regard for the safety of passengers and crews, but did not always obey them. On 3rd September, for example, the submarine U.30 sank the passenger liner Athenia off north-west Ireland at the cost of 112 lives. In the whole of September 41 ships, aggregating 153,879 gross tons, were sunk by German submarines.11

The Allied answer was to introduce the system of convoy planned before the war. But escort vessels were scarce, while Coastal Command, preoccupied with its programme of North Sea reconnaissance, had few aircraft to spare for convoy escort. Consequently some groups of ships were forced to sail unescorted. Moreover, aircraft had little chance of spotting submarines unless they surprised them on the surface. Even then the quarry had only to dive in order to become virtually safe from an attacker who carried no depth-charges and whose bombs were few and small. Nevertheless seven submarines were sunk by various means in the first two months of war.12 As winter drew on, the U-boat offensive dwindled, not so much because of sinkings as because the weather grew less favourable and because an ambitious programme of minelaying absorbed much of the German effort.

But if the winter brought a temporary alleviation of one problem of maritime defence, it promised no relief from others. The fear that German surface raiders would try to gain the High Seas proved better founded than faith in the system designed to stop them. Leaving Wilhelmshaven on 21st August, the pocket-battleship Admiral Graf Spee slipped into the Atlantic a few days later, while our general-reconnaissance squadrons were grounded for a final inspection before beginning their North Sea patrols.13 On the 24th her sister ship, the Deutschland, left the same port. Helped by thick weather, and making the best use of darkness, she too escaped detection. In September replacement of Ansons by Hudsons enabled the air reconnaissance patrols to be carried almost the whole way to the Norwegian coast; but in general the patrols were ineffective.14 A radar set with which aircraft could detect surface vessels in darkness or thick weather was under development but not yet in use; meanwhile patrols were discontinued at night, and in the daytime were often defeated by cloud, fog or heavy rain. On 8th October a Hudson of No. 224 Squadron from Leuchars spotted a German naval force—the battle-cruiser Gneisenau, the cruiser Köln and an escort of destroyers—near the coast of Norway; but the Deutschland, returning to the Baltic in November, was missed once more. In the same month the battle-cruisers Scharnhorst and Gneisenau cruised for some days in the Atlantic, also without detection as they came and went. Meanwhile the escape of the pocket-battleships, coupled with the demands of the U-boat campaign, the conveyance of the Expeditionary Force to France and other tasks, had caused a wide dispersal of Allied naval forces.

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Moreover, British warships and their bases soon proved more vulnerable than had been expected. To make up for the shortage of escort vessels and shore-based aircraft for convoy escort, towards the middle of September the aircraft-carriers Ark Royal, Courageous and Hermes were ordered to cruise in the Western Approaches so as to provide a measure of protection for shipping there. On the 14th the Ark Royal narrowly escaped sinking by the submarine U.36; on the 17th the submarine U.29, encountering the Courageous at an unhappy moment when she was flying-on her aircraft and was inadequately protected, sank her. A month later the submarine U.47 exposed the inefficacy of the local naval defences at Scapa Flow by entering the Flow through a channel that had been left inadequately guarded; on the morning of the 14th she sank the battleship Royal Oak, lying at anchor about a mile from the shore.

Two days after the sinking of the Royal Oak, nine aircraft of Kampfgeschwader 30 attacked warships in the Firth of Forth, doing slight damage to two cruisers and a destroyer. It happened that on this occasion the system of early warning worked unsatisfactorily; and while the silence of the public air-raid sirens could be justified on the ground that no attack on the mainland was expected or in fact took place, the failure of the local Gun Operations Room to receive notice of the enemy’s approach until some of the guns had opened fire was not so easily explained away.15 A moment after the warning had been tardily received, the enemy appeared over the Forth Bridge. All guns not already firing were then called to action. The gunners at one site were engaged in gun-drill when they saw a German aircraft near them, and had hastily to exchange their dummy ammunition for live. The Spitfires of Nos. 602 (City of Glasgow) and 603 (City of Edinburgh) Squadrons of the Royal Auxiliary Air Force joined the guns in shooting down two bombers—the first destroyed over or near the United Kingdom since the beginning of the war.*16

Next morning aircraft of the same German unit raided Scapa Flow. In the absence at sea of the Home Fleet they attacked and damaged the depot-ship and former battleship Iron Duke, which was subsequently beached. One bomber was hit by anti-aircraft fire and crashed on the island of Hoy.

On the whole the destruction of three aircraft in the two raids was a satisfactory achievement, but the performance of the early-warning system was less so. Where the guns were concerned, the verdict of General Pile was that evidently neither the standard of training nor the equipment of his command was yet up to the standards of modern war.17

* As a result of the action No. 603 (City of Edinburgh) Squadron (Squadron Leader E. E. Stevens) was officially credited with the destruction of the first aircraft destroyed by Fighter Command. At the time four German aircraft were believed to have been destroyed.

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The exploits of U.47 and Kampfgeschwader 30 showed that Scapa Flow was not yet a secure base for the Home Fleet. Before it could be so regarded, the local naval defences must be extended and improved, and stronger air defences must be provided. These tasks could scarcely be completed before the early spring. Meanwhile the Fleet must move elsewhere, though Scapa would still be put to occasional use. To provide some measure of fighter defence while the Fighter Command squadrons promised for 1940 were awaited, the Admiralty arranged to send two naval squadrons to a neighbouring aerodrome.18

Rosyth was a possible alternative, but was a little too far south to be altogether satisfactory, and its approaches were vulnerable to mining.19 For the next five months the Fleet was therefore compelled to make use of remote anchorages on the West Coast of Scotland.

Within two months of the outbreak of war the Government were thus confronted with a situation rather different from that for which their plans provided. Allied naval resources were widely dispersed; the Home Fleet was without its best strategic base and on the wrong side of Cape Wrath; and the system of North Sea reconnaissance had been found wanting. Attempts to bomb German warships at sea had failed in recent weeks20 and might succeed no better in the future. In short, control of the North Sea had been lost, at least for the time being. Thus invasion could no longer be ruled out on the old ground that a hostile expedition would be infallibly detected by air reconnaissance and would be ‘bombed and shelled to destruction’ before arrival, though it might still be thought unlikely for other reasons. Moreover the German Chancellor, meeting with no response from the British Government to his offer of peace terms after the defeat of Poland, might be expected to grow more belligerent.

In the light of these considerations the War Cabinet decided in October that the risk of a landing by German forces which might slip past the navy and Coastal Command during the longer nights of winter was not to be ignored.21 They asked the Chiefs of Staff to reconsider the danger and take steps to meet it.

After studying the matter at some length, the Chiefs of Staff came to the conclusion that small raids were possible, and invasion proper conceivable, but that neither threat was serious enough to justify them in keeping back field formations intended for use elsewhere.22 To meet the Government’s wishes they proposed that ‘a suitable proportion’ of such troops as would normally be at home should be disposed within easy reach of the East Coast, and that plans should be made for their rapid concentration if the need arose. Special air and naval reconnaissance to give warning of the assembly and passage of a large seaborne expedition could, they implied, be deferred until the danger became imminent. They also recommended a number of measures

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designed to strengthen the defences of ports and aerodromes, but added that most of them were already in hand. Their mention of an ‘adequate air striking force in a state of readiness’ suggests that the practical difficulty of co-ordinating reconnaissance with offensive action, and the frequent inability of bomber crews to find or hit their targets, were even yet not fully grasped; though admittedly the Chiefs of Staff went on to point out that communications, and co-operation between different branches of the defences, must be improved.

Thereafter until the spring of 1940 the country’s landward defences against invasion or minor raids were governed by a new scheme called the JULIUS CAESAR plan. Its basis was the dual assumption that the landing of seaborne troops in any number presupposed the early capture of a port, and that parachutists or other airborne forces would play a vital part in any attempt that the enemy might make.23 Further assumptions were that a seaborne force of one division could be carried in twenty transports of 4,000 to 5,000 tons, which could make the crossing in 20 hours and would be escorted by 25 to 30 modern destroyers.* German resources for an airborne operation were estimated at 1,000 transport aircraft, 4,000 trained parachutists and 6,000 trained air-landing troops.† Any attempt at a major landing would probably be supported by a heavy air offensive against the Home Fleet, the Royal Air Force and ‘other objectives in this country’.

General Kirke believed that if the airborne force were defeated the battle would be won. Deprived of its support, the seaborne force would, he thought, find landing so hazardous that the assault would fail.24 Accordingly his plan laid emphasis on the prompt annihilation or capture of parachutists and other airborne troops as they descended or were assembling on the ground. Bodies who nevertheless succeeded in establishing themselves on British soil would be either surrounded by a cordon, or broken up by armoured troops or horsed cavalry. As an additional precaution against capture of a port from the landward side, Scottish, Northern and Eastern Commands were ordered to allot infantry for the local protection of ports and their fixed defences in their respective areas. Should the enemy land, Home Forces would have the direct support of two bomber squadrons, besides an Army Co-operation squadron and three communication aircraft. In the meantime a small bomber force had stood by since the outbreak of war to attack German naval targets as opportunity arose; and in an emergency all home-based bombers would in theory be available to engage a hostile expedition before departure or on passage. There

* In fact, some 50 to 60 transports of that tonnage would have been required, and the crossing could scarcely have been accomplished in less than 36 hours. The German navy had about 20 destroyers.

† These estimates were approximately correct.

Plate 1

Plate 1. Air attack on British warships in the Firth of Forth, 16th October 1939.

Plate 2

Plate 2. Preparing to fire a 3-7-inch Mark II Anti-Aircraft Gun (Static Mounting).

Map 5: Disposition of 
Home Forces, 1 May 1940

Map 5: Disposition of Home Forces, 1 May 1940

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would also be a few torpedo-bombers under Coastal Command. In practice, attempts to bomb the German fleet in harbour or at sea were almost uniformly unsuccessful, and were suspended in December while protective armour was fitted round the fuel-tanks of the aircraft used.25 Meanwhile the Admiralty had decided that precautionary air patrols over the southern part of the North Sea were advisable, even though the imminent danger postulated by the Chiefs of Staff was not in view. Begun on 29th October, the patrols were continued through the winter for the additional purpose of investigating movements of German minelayers and other suspicious craft.26

Before the war invasion had seemed so slight a risk that in 1937 entries bearing on the withdrawal of civilians from threatened areas had been deleted from the Government War Book, despite a reminder from an experienced source that a similar decision before the First World War had led to unpreparedness.27 Once again the matter had to be reconsidered now that war had come. The decision reached was that civilians not in immediate danger should be encouraged to stay where they were; those more vulnerably placed would be withdrawn by routes designed to interfere as little as possible with military traffic.28

General Kirke put the troops needed for JULIUS CAESAR at not less than one division each in Northern and Scottish Commands, two in Eastern Command and three in reserve, or a minimum of seven altogether.29 The forces at his disposal in November, apart from those performing static tasks, comprised nine infantry divisions and elements of three more, one cavalry division, one armoured division and an armoured brigade, with 25 cruiser and 267 light tanks.30 ln general these formations were inadequately trained and equipped for mobile warfare. Furthermore the best of them could expect to be ordered abroad as soon as they were ready for despatch.

At the beginning of May 1940, by which time the 1st Cavalry Division had left for the Middle East and the 1st Armoured Division was nearly ready to go to France, nine weak or inexperienced divisions, including the 2nd Armoured Division, were available to carry out the plan.31 Among them were the 1st Canadian Division, which had arrived in January. Other formations under General Kirke included three training divisions and four divisions earmarked for special tasks. Map 5 shows how these forces were disposed.


Meanwhile a new danger had arisen. From the start of the war German submarines and surface craft, defying the convention which prohibited undeclared minefields dangerous to peaceful shipping,

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began to lay mines in British coastal waters.32 Within the first week the Admiralty suspected that some at least were of the magnetic type, designed to rest on the bed of the sea until the magnetic field of an approaching ship made them active. The Royal Navy had used magnetic mines in 1918, and the possibility that other powers might use them in the future had been considered on numerous occasions since that time. Nevertheless no effective steps to guard against the danger had been taken, chiefly because a lack of funds prevented the Admiralty from providing for all contingencies. On the outbreak of war the whole of the minesweeping fleet immediately available was equipped to deal solely with contact mines, and plans for its expansion were based on the assumption that magnetic mines would not be used. Moreover the risk that surface craft might be employed to lay mines in our coastal waters had not been seriously considered. In September and October 59,027 tons of shipping were sunk by mines off the East Coast, in the Thames Estuary and elsewhere.33

A fully effective answer to the threat demanded detailed knowledge of the German weapon. Nevertheless a good deal could be done without such knowledge. Service and civilian experts were put to work on the problem of sweeping magnetic mines; plans for a magnetic sweep and for the construction of a ‘mine destructor ship’, which had been projected some months before the war but shelved for lack of funds, were revived in a new form; and steps were taken to make shipping less vulnerable by altering or suppressing the magnetic field with which every metal ship is endowed in the builder’s yard. Apart from their practical value, which was somewhat overrated, ‘wiping’ and ‘degaussing’, as the alternative methods of treating ships were called, had an important moral effect on Masters and crews of merchant vessels, some of whom are said to have attributed to these mysteries the power of warding off torpedoes. As for sweeping, the method first tried employed ships with huge magnets in the bows; it proved uneconomical and hazardous. That eventually adopted consisted of a double sweep by two ships, each towing a pair of buoyant cables so arranged as to explode the mines at a safe distance. The problem of making a suitable cable was successfully tackled by two British cable companies after some authorities had pronounced it insoluble.

In November seaplanes began to supplement the efforts of the German navy by dropping magnetic mines attached to parachutes. The first expedition for the purpose was made on the night of the 18th by aircraft of Küstenfliegerstaffel (Coastal Reconnaissance Squadron) 3/906, but was abandoned because of unsuitable weather.34 On the night of the 20th the same squadron laid mines off Harwich and at two points in the mouth of the Thames, supposedly in the King’s Channel and the Black Deep. The seaplanes dropped their mines

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from heights of the order of 3,000 feet, but were not engaged by guns or fighters, although some searchlights were in action. The squadron again dropped mines on the next night, and on the 22nd were joined by seaplanes from another coastal reconnaissance squadron, Küstenfliegerstaffel 3/106.

On the third night watchers on shore near Southend saw an object fall into tidal water. At the time its nature could only be guessed; but it was in fact one of the mines dropped by Küstenfliegerstaffel 3/106. The Admiralty were informed, and within a few hours a party headed by Lieutenant-Commander J. G. D. Ouvry of H.M.S. Vernon left to look into the matter. In the small hours of 23rd November the receding tide revealed the mine and steps were taken to secure it. The next low tide revealed a second mine and enabled Ouvry and his helpers to undertake the delicate task of stripping the first of its detonator and other essential fittings with special non-magnetic tools which had been hastily made locally. The mine and fittings were then landed and taken to the Naval Mine Department for further dissection.

The knowledge thus gained was a major contribution to the devising of effective counter-measures. From the German viewpoint the opening contribution of Küstenfliegerstaffel 3/106 was doubly disastrous, for it not only presented the adversary with the mine itself but also revealed the presence and purpose of the seaplanes to the defences. Nevertheless the interception and destruction of aircraft engaged in minelaying remained until the end of the war extremely difficult, for the machines were not bound to cross hostile coasts and could often escape detection by remaining only just above the surface of the sea.

Offensive counter-measures to minelaying by German seaplanes included patrols over their bases by Blenheim fighters and Whitley bombers (replaced in the early part of 1940 by Hampden bombers). On the night of 19th March Whitleys and Hampdens aimed some fifteen tons of bombs at a seaplane base at Hornum, on the island of Sylt, as a reprisal for one of Geisler’s raids on Scapa Flow, but the Luftwaffe unit stationed there reported little damage. Aircraft in the shape of Wellington bombers fitted with magnetic loops energised by generators which they carried with them, and manned by Coastal Command crews, also contributed to sweeping, making their first successful sortie on the night of 8th January, 1940, and continuing to take a valuable share of the work while more strictly naval measures were getting under way.

In the outcome the harrying of minelayers on, under and above the water, preventive treatment of friendly shipping and, above all, the keeping open of swept channels, all contributed to victory over the magnetic mine. In the first six months of the war the navy swept

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74 such mines; in the next three they swept 213. The Germans then turned to the acoustic mine, also a weapon studied by the Admiralty during the First World War. Once again the problem of devising counter-measures was eased by the recovery of mines dropped by German aircraft near the shore. Minesweepers were fitted with road-drills whose ear-splitting din exploded the mines at a comparatively safe distance, and other ships with loudspeakers or pneumatic hammers. In view of the obvious preference shown by the Germans for non-contact mines, possible variants of both weapons were explored, with the result that the Admiralty were ready with counter-measures or able to devise them quickly when the need arose in later years.


Meanwhile the absence of heavy air attacks on the United Kingdom gave the air defences a valuable breathing space. During the first four months of war the number of heavy anti-aircraft guns available for home defence increased by about a fifth and the number of light anti-aircraft barrels doubled.35 The supply of searchlights kept pace with new demands, but the total available remained at the end of 1939 about 1,400 short of the approved scale. On the other hand, Balloon Command suffered a setback. Losses due mainly to sudden changes in the weather far exceeded expectations; and as current production was not large enough to make them good, the squadrons were forced to conserve their stocks by keeping about two-thirds of their balloons deflated.36 The return of the Deutschland to Germany in November, and the scuttling of the Graf Spee in the River Plate in December after she had been cornered and damaged by British cruisers, eased the home defence position somewhat, since it freed important naval forces—amounting in October to four British and French battleships, five aircraft carriers and fourteen cruisers— which had hunted or lain in wait for the two ships. In the circumstances there may have seemed little reason throughout the late winter and early spring to question the adequacy of the JULIUS CAESAR plan to ward off invasion or lesser expeditions.

On the other hand, the threat of an all-out air attack still hung over the United Kingdom, and Air Chief Marshal Dowding was far from satisfied that his resources were strong enough to meet it. Although aware of the Air Staff’s proposal to send four fighter squadrons to France with the Air Component, he had continued until the outbreak of war to hope that they would not leave the country until all fifty-three of the squadrons contemplated in the final peacetime plan of air defence were in existence.37 In the outcome he not only lost the four squadrons, but was ordered to put six more on a mobile footing

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against the day when further demands from the Expeditionary Force could no longer be resisted. Apart from the immediate effect on his resources, he foresaw that casualties suffered across the Channel when fighting began would have to be made good from reserves or new production which might be urgently needed for home defence. Moreover, he had personal grounds for his uneasiness. Shortly before the war he had been asked to broadcast a reassuring message to the nation, and had done so under the mistaken impression that all the fighter squadrons mobilised would remain at his disposal for some time to come.

On 16th September, after interviews with the Secretary of State for Air and the Deputy Chief of the Air Staff had failed to satisfy him, he therefore made a formal protest, in which he likened the despatch of the four squadrons to the opening of a tap through which the whole output of Hurricanes would ultimately be drained away.38 During the next few weeks he repeatedly urged the Air Ministry to resist further demands from France and concentrate on building up his strength to withstand the ‘knock-out blow’ which he thought was bound to come. His view was that the needs of Fighter Command deserved absolute priority over other claims, for he argued that defeat at home would make the strengthening of other commands a useless sacrifice. If the country were knocked out by air attack, nothing Bomber Command or the forces in France could do would be likely to retrieve its fortunes.

The Air Ministry did not accept these arguments. Although they had been obliged in the previous year to put fighters before bombers, they still believed that the best contribution they could make to victory was a powerful bomber force. At the same time they felt bound to support the Franco-British armies to the best of their ability.39 Nevertheless they agreed that demands from France must not be allowed to cause ‘an unwarrantable drain on the available resources’. They consented, therefore, to allay the worst of Dowding’s fears by laying down the principle that supplies of Hurricanes should be divided between Fighter Command and the squadrons across the Channel in the ratio of three to one; and they sanctioned measures designed to strengthen the fighter force a little and make its immediate future slightly less dependent on that aircraft. Six half-squadrons of Blenheims would be formed immediately, and would become full squadrons as soon as possible; at the same time Gladiator squadrons would be substituted for two of the six Hurricane squadrons earmarked for despatch abroad. Only when the output of Hurricanes had improved were these two squadrons re-equipped with the more modern aircraft.

But requests from France, and the manifest likelihood that before long more would have to be done for an expanding Expeditionary

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Force, soon forced the Air Staff to go further. Foreseeing that much pressure would be put upon them to send more fighters across the Channel if German armies attacked France or the Low Countries, they decided in October to form ten more squadrons by the middle of November, besides the six already promised and another two to fill the gap caused by the departure to France of the first two of the six squadrons earmarked.

In practice, formation of all eighteen of the new squadrons proved impossible before the middle of December. By the 18th two of them had been added to Dowding’s first-line strength and the rest were working up. But a number were temporarily equipped with obsolescent aircraft which would have to be replaced before the squadrons could be reckoned fit for active service.

Thus by the end of 1939 Dowding, having lost six squadrons and gained eighteen since the beginning of the war, had 51 of the 53 which were Fighter Command’s target. About a third of his force was not yet fully trained, but might perhaps be ready by the time the enemy attacked. With the six in France, the fighter force as a whole stood at 57 squadrons.

Unfortunately it did not follow that attainment of the target would give Dowding all he needed, for his responsibilities were growing. So far Geisler’s attacks on merchant shipping had done no damage comparable with that inflicted by magnetic mines, but his force was a constant threat to local convoys, mine-sweepers and naval flotillas in coastal waters. In general, the convoy-routes passed close inshore; but even so the normal practice of despatching fighters to deal with approaching bombers when they were detected by the radar chain was not enough to protect the ships that used them. When the defeat of Poland brought the fear that British rejection of German overtures might be the signal for heavier attacks on shipping, Dowding strengthened his forces near the East Coast, but pointed out that interception, of bombers several miles from the shore could not be guaranteed.40 The convoys needed fighters which would stay near them as long as they were in danger.

The Air Ministry responded by forming the four trade-protection squadrons projected just before the war. Obviously four squadrons of Blenheims would not be enough to give strong and continuous escort to all East Coast convoys; but the Air Staff hoped that even one or two long-range fighters with each convoy would perform a useful function by serving as rallying-points for Dowding’s short-range high-performance aircraft.41 Dowding did not welcome the addition, fearing that the new task would conflict with his command’s essential duty of guarding London and the aircraft industry. On the other hand the Blenheims would be invaluable to Air Marshal Bowhill of Coastal Command; for the Admiralty, having somewhat modified

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their view that warships could look after themselves, were pressing for air cover by shore-based aircraft in waters within reach of Geisler’s bombers. Assailed on two fronts, the Air Ministry conceded that the squadrons should move to Coastal Command, at least for the time being.42 ln the outcome they remained in Coastal Command throughout the war, except for a brief period in 1940 when Dowding used two of them to strengthen weak parts of his fine on the South Coast and in Scotland.

Unfortunately for Dowding’s hopes, the burden of guarding coastal convoys did not move with the trade-protection squadrons. Bowhill used the squadrons chiefly for reconnaissance and for covering naval movements. In any case he lacked the short-range high-performance fighters which alone could provide the real answer. Hence the change did little to lighten the task of Dowding and his staff, whose only remedy was to find some way of discounting the shortcomings of the short-range fighter as a means of continuous protection for slowly-moving targets.

The solution adopted was to ring the changes on three methods, according to the degree of danger and the importance of the convoy. The least burdensome method (called ‘fighter cover’) required merely that Air Officers commanding or their deputies in the operations rooms of the command should note the position of convoys from time to time and should be specially prompt in sending fighters to deal with hostile aircraft shown by radar to be approaching them. Apart from the risk that the enemy might escape notice by flying very low, a great weakness of fighter cover was that the best method which could be devised for tracking convoys did not accurately disclose their positions at every moment. The ships and their escort could not themselves provide the information without betraying it to the enemy, and hence were bound to silence until attack seemed imminent. Consequently convoys guarded only by fighter cover were sometimes attacked when groups did not suspect that they were threatened, so that fighters sent only when a call for help was made arrived too late. On the other hand, the method was cheap, and entailed no departure from the normal practice whereby a small number of fighters was held constantly at readiness in every sector.

A second method, called ‘fighter protection’, was more exacting but avoided some of the penalties of standing escort. In each sector concerned, fighters other than those normally at readiness were detailed to protect a given convoy while it passed along the stretch of coast for which the sector was responsible. They did not accompany the convoy, but took up a position assigned by the group commander or controller, who might even allow them to remain at their base if he had no reason to suppose that the ships would be attacked. In

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favourable conditions they were thus able to keep watch with little expenditure of fuel and without adopting a patrol-line dictated by the movement of the convoy; but again ships’ crews, unless attacked, did not enjoy the moral advantage of seeing their protectors near them. Regulations designed to lessen the risk that ships might be surprised by German bombers virtually prohibited fighters from going within about three-quarters of a mile of merchant vessels, or six miles of a warship, unless they were in contact with the enemy.

Finally there was ‘fighter escort’. Where this method was employed the ban was lifted and the fighters assigned to a given convoy stayed with it until relieved. Fighter escort was the method generally preferred by seamen, but was inherently extravagant and not much liked by fighter pilots. Always at a disadvantage over water unless at a good height, the pilot of a single-engined landplane was trebly handicapped when tied to a slowly-moving mass of ships whose surface escort bristled with suspicion of any object which looked as if it might drop bombs. If he remained low enough and close enough to the ships to put his identity beyond doubt, he might be caught at a tactical disadvantage and would probably be unable to reach the shore in an emergency. If he interpreted his instructions more liberally and improved his tactical position by gaining height and going further from the convoy, he ran the risk of being fired upon by his own side when he returned. In time the better education of ships’ gunners in aircraft recognition, and a better understanding between the services, did much to improve his chances, but they did not lessen the essential wastefulness of standing escort by high-performance fighters.

Hence there could be no question of giving escort wherever help for shipping was requested. Standing escort for all shipping in vulnerable areas throughout the daylight hours would have saddled the fighter force with so intolerable a burden as to render it unfit for a major battle. On the other hand coastal convoys, naval flotillas and important traffic across the Channel could not always be left with no better defence than that provided by the interception system and by such anti-aircraft armament as the ships might carry. Thus Dowding was forced to compromise, adjusting his support to needs and risks. At first the choice was often difficult, for the naval liaison officers attached to his headquarters were not qualified to assess competing claims; moreover requests for air support were sometimes made direct to his subordinate formations. Later he was able to improve matters by adding a senior naval officer to his staff and by exacting a promise that all requests should be addressed to Stanmore. Meanwhile the number and urgency of the requests were such that his jealously-hoarded squadrons were obliged to fly about a thousand sorties for the direct defence of shipping in each of the last three

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months of 1939, and in each of the first two months of 1940 more than twice that number.*43

For this reason, and also on other grounds, the outlook at the beginning of the New Year seemed to Dowding far from promising. No big attacks had yet been made on the United Kingdom; but the blow might fall at any moment. Already the threat to shipping had forced him to extend his left flank by basing squadrons north of the Tay, and he saw no prospect of withdrawing them.44 Moreover his calculations did not exclude the risk that in the spring the Low Countries or even France might be overrun by German troops. In either case the Luftwaffe would be able to strike over a wider area. Meanwhile there was some evidence that its leaders meant to do so from existing bases by using aircraft of longer range than their normal long-range bombers. A prisoner taken in January alleged that his superiors intended to set up a unit capable of reaching the Western Approaches, apparently from German bases.45 He gave its name correctly as Kampfgeschwader 40, although the aircraft he assigned to it proved troublesome and were not used until much later. In the same month the German Air Ministry raised the status of Geisler’s command for the second time since the outbreak of war, and reports that his resources were to be increased reached London and were passed to Stanmore. They proved well founded, though in the outcome the augmented force was used for the Scandinavian campaign which came in April.

A consequent request from Dowding that the Air Staff should review the needs of air defence found them already engaged in such a study. They noted that since the beginning of the war the defences claimed to have shot down thirty German aircraft—an estimate more or less confirmed by various sources at the time and now known to have been substantially correct.†46 The number which had come within their reach was estimated at not less than 100 and not more than 300. Thus at least a tenth and perhaps nearly a third of the attackers had been destroyed while in search of ships and harbours. Superficially it seemed fair to assume that attacks on inland targets would bring a higher rate of loss.

As combat losses exceeding ten per cent, of the attacking force were widely held to approach the prohibitive if long continued, thus far the argument tended to show that the defences needed no improvement. But much else had to be considered. Whether the enemy increased his range or not, the flanks of the defensive system lacked

* A sortie is one flight by one aircraft; a patrol one flight by any number of aircraft. Thus a patrol by two aircraft counts as two sorties.

† During the period in question the Luftwaffe lost 46 aircraft in operations against the United Kingdom and shipping in adjacent waters. Of these losses, a minimum of 27 and a maximum of 32 were attributed by the Germans to the defences, the rest to other causes such as accidents.

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depth, and local defences there and elsewhere were generally weak for want of guns. Success against small forces which hardly crossed the coast might therefore be a misleading index of ability to cope with larger forces bent on penetration. The country’s war potential was growing; factories and stores were springing up in remote parts of the kingdom, so that places yesterday obscure were to-day important, and to-morrow might perhaps be easily assailable. At the lowest estimate there seemed to be a good case for the formation of a new fighter group in the south-west, which had been projected before the war. That another would soon be needed to bridge the gap between the northern flank and the outpost at Scapa Flow was highly probable. Moreover the Air Staff, taking a gloomier view than events were afterwards to justify, calculated that by the autumn of 1940 the enemy would have well over two thousand bombers, and six months later about a thousand more.47 It followed that sooner or later the fighter force would have to be increased, and there was much to be said for planning its expansion in such a way as to keep pace with the formation of any new groups which might be in view. For the new groups would be of little value if Dowding was so short of fighters that he could not count on furnishing them with squadrons.

Accordingly in March Air Commodore D. F. Stevenson, Director of Home Operations, recommended that seven new fighter squadrons should be formed at once and another twenty within the next twelve months.48

However good these arguments, the conclusion was not one which the Air Staff as a whole could be expected to accept without reluctance. When putting forward the original scheme of air defence in 1922, and again before the Salisbury Committee in 1923, their predecessors had stressed the importance of bombing.49 The fighter force, they urged, was a subsidiary weapon, likely to be invaluable during the awkward period while the bomber offensive was getting under way, but always to be kept as small as possible. At any rate in theory, they had never departed from that doctrine. Even after the advent of radar had revolutionised the possibilities of pure defence, they had continued to regard a powerful striking force, erected on the modest framework of the peacetime Bomber Command, as their main weapon. Accordingly the outbreak of war should have been the signal for a great expansion of the bomber force and all its services. But in fact the manifold claims of war had precluded any such expansion, so that instead of being larger than in 1939 the bomber force was three squadrons smaller, and well behind the peacetime programmes. If Stevenson’s recommendations were accepted its expansion would be still further delayed.

Moreover there was no certainty that the aircraft industry would be able to maintain a fighter force of the size proposed. At the end of

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the third week in February the Aircraft Storage Units held only sixteen Spitfires and Hurricanes immediately ready for active service; in the whole of that month the output of single-engined aircraft was 143.50 Two months later the outlook was so unpromising that Air Marshal Courtney, the member of the Air Council responsible for supply and maintenance, found it necessary to propose a fortnight’s halt in re-equipment with new aircraft in order that his department might have some chance of building up a small reserve.51

Irrespective of any theories about the relative importance of the bomber and the fighter, probably the only course the Air Ministry could reasonably have taken, short of somehow engineering a spectacular increase in production, was a compromise. At any rate that was the course they took. They approved substantial additions to Fighter Command’s ground organisation, but deferred the formation of new fighter squadrons until they could see what dislocation of supplies was likely to result.52

There the matter stood in early May, when reports that the Germans—who had already struck at Norway—were about to launch their main offensive in the west became increasingly circumstantial and persistent. If the Expeditionary Force were heavily involved in France or Belgium, demands for more fighters in that theatre would certainly be made and could scarcely be resisted. To meet them without grave prejudice to home defence would be impossible unless Fighter Command had a margin over present needs. On the 8th the Air Ministry bowed to the inevitable. They sanctioned the immediate formation of three of the seven squadrons proposed by Stevenson in March, and arranged to discuss the other four at a meeting two days later.53

Thus the opening of the battle for Western Europe on 10th May found the Air Ministry on the eve of a modest expansion of the fighter force, while ahead of them loomed formidable problems of production and supply. The meeting planned for that date was postponed for six days while the Air Staff grappled with issues more urgent but scarcely more important.

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