Chapter 4: The Eve of the War
WE LEFT the air defences at the point where the Government, abandoning the principle of ‘business as usual,’ authorised the Air Ministry to order virtually all the aircraft they could get. On the assumption that financial considerations could be disregarded, the maximum output of the aircraft industry, working on double shifts, was estimated in the spring of 1938 at 4,000 machines by April 1939, and 8,000 in the following twelve months.1 More could not be expected from factories long starved of orders, and even in 1938 employing little more than a quarter of the hands employed at the height of the First World War, when aircraft could be built with about one-tenth of the effort now required.2
Scheme L of 1938 was designed to provide 73 bomber and 38 fighter squadrons by the spring of 1940. The full programme was:
|METROPOLITAN AIR FORCE|
Reserves would be provided for fighter and general-reconnaissance (including flying-boat) squadrons on a scale designed to cover sixteen weeks’ wastage in time of war, and for other squadrons on a scale designed to cover nine weeks’ wastage. The establishments of bomber, fighter and general-reconnaissance (other than flying-boat) squadrons were made substantially larger than those contemplated in Scheme F, so that (for example) the addition of only eight squadrons to the fighter force increased its nominal first-line strength by nearly one-half. While the fighter force would undoubtedly gain in
staying-power if these additions were made good, its squadrons would not normally go into action with more than twelve aircraft at a time.
The strength and weakness of the new scheme can be summed up very briefly. On the one hand, it promised to make good use of a limited industrial capacity, though a possible criticism is that too much emphasis was laid on bombers, which took a relatively long time to produce and which would be less valuable at the outset of a war than the fighters needed to secure the base. On the other hand, it would give in two years’ time only about three-quarters of the fighter squadrons needed for the ‘ideal’ programme, and only about the same bomber strength as Germany was expected to achieve within the next few months.
These shortcomings were the more disturbing since other components of the air defence scheme threatened to fall far short of requirements. In 1936 the War Office had warned the Government of the long time that must elapse before their new 4-5-inch and 3-7-inch anti-aircraft guns were ready.3 In 1938 the guns were beginning to arrive, but shortages of skilled labour and materials gave little hope that output could be accelerated..4 The reconditioned 3-inch guns, with their rather old-fashioned ammunition, were scarcely fit to cope with modern aircraft, and even they were none too plentiful. That Scheme L ‘fell below the level of safety’ which they thought necessary was, indeed, quite clear to the Air Staff,5 nor could the Government deny that attempts to achieve parity with the German air force had failed.
In retrospect an increase in the fighter force at the expense of the heavy bomber squadrons may seem an obvious solution. But in the early part of 1938 that course would not have appealed to the Air Staff. Their faith in bombing had survived the replacement, as the hypothetical aggressor, of France—whose aircraft factories, conveniently clustered near Paris, might have made good targets—by the less accessible enemy beyond the Rhine. Admittedly German heavy industry was concentrated in the Ruhr, which even medium bombers could reach from forward bases. But would such attacks on the Ruhr as the British bomber force could make within the next few years be an effective answer to a knock-out blow on London? And would such attacks be possible at all if the base was not more securely guarded than it promised to be under the existing programme?
The shortcomings of British air power were much in the minds of statesmen while Scheme L was current, and in the spring of 1938 some of them were freely ventilated in Press and Parliament. At the same time, measures of maritime defence were a long way from completion, and British participation in a land campaign to secure the integrity of the Low Countries was still uncertain.
To the German Government, who had incurred no penalty two
years before by remilitarising the Rhineland in defiance of the Treaty of Versailles, conditions may have seemed ripe for a display of power. In the spring of 1938 their troops marched into Austria; thereafter they advanced a claim to parts of Czechoslovakia whose population was predominantly German, but whose loss would strike at the root of the strategic plan by which France and her Eastern European Allies hoped to check the eastward expansion of the potential enemy. In the autumn the German attitude became so threatening that the British Government ordered an emergency deployment of a great part of the home defences.
The deployment was not a full-dress rehearsal for mobilisation. Neither a state of hostilities nor the ‘precautionary period’ for which the various departments of State had drawn up plans was deemed to have begun. In some respects conditions were less favourable for rapid moves of units than they might have been if emergency measures had been applied more widely. Nevertheless the experience provided a convincing demonstration of unreadiness for war. In Fighter Command twenty-nine fighter squadrons were reckoned mobilisable, but only five of them had modern aircraft. Even those five were incapable of fighting at high altitudes, for their guns had not yet been modified to work above 15,000 feet. There were also five squadrons of Gladiators, old-fashioned in appearance and no match for modern fighters, but capable of engaging bombers. The rest of the fighter squadrons had obsolete or obsolescent aircraft.*6 There were no stored reserves of fighter aircraft; immediate reserves with squadrons and in workshops amounted to about two-fifths of first-line strength. The radar chain gave partial cover only between the Wash and Dungeness, communications were incomplete, and the whole command was dependent on radio equipment much inferior to that which replaced it in 1939 and 1940. The London balloon-barrage was only about one-third ready—142 balloons were deployed towards an establishment of 450—and its deployment raised many problems, not all of which had been foreseen.7 The state of the anti-aircraft and searchlight formations was still worse. Nearly 50,000 Territorials joined the air defence and coast defence formations when summoned, but only about one-third of the anti-aircraft guns and lights proposed by the Reorientation Committee in 1937 were available.8 Some of them were not in working order or were accompanied by unsuitable ammunition or equipment. The majority of the guns were of the obsolescent 3-inch pattern, some fifty 3-7-inch and no 4-5-inch pieces being ready. Arrangements for billeting and the issue of stores left much to be desired.9 Measures of Civil Defence were hampered,
* The 29 squadrons were equipped as follows: Hurricane 5, Gladiator 5, Fury 3, Gauntlet 9, Demon 7.
according to the Air. Raid Precautions Department of the Home Office, by undue regard for secrecy.10
Arrangements for maritime defence were also far from satisfactory. Whereas the navy mobilised, the air force did not; and of the twelve squadrons of Coastal Command considered fit for active service, eight had to move over an average distance of 270 miles without the benefit of war establishments. Only the help of naval and army reservists, and of officers’ wives who were hastily pressed into service and had to be taught by officers with too much to do already, made it possible to maintain communications for the brief period of the crisis. Again, a lack of spares would soon have kept some squadrons on the ground if the emergency had been prolonged. Destroyers and escort vessels were scarce, trawlers needed for minesweeping could not have been made ready for action in less than three weeks, the coast defences at several naval ports were manifestly inadequate and much of the berthing space at Rosyth was silted up, as were the naval harbours at Dover and Harwich.11 Despite the lesson of the Shanghai incident, stocks of oil fuel at home and abroad were still unprotected; and lack of storage space compelled the navy to disperse its reserves of ammunition largely in ships and trains.12 On the other side of the account, German naval strength was low but the much-feared Luftwaffe had a thousand serviceable bombers.*13
The crisis was ended by negotiations culminating in the Munich agreement, whereby France and Great Britain purchased a respite at the cost of some thirty Czech divisions. Notwithstanding the reassuring words with which the Prime Minister returned from Munich, preparations for war were afterwards conducted with new energy. In the sphere of maritime defence, steps were taken to ensure concurrent mobilisation of the navy and the air force; the system of operational control through Area Combined Headquarters was elaborated; and
* The following table shows establishments and strengths of Luftwaffe units on 26th September 1938, and the numbers of serviceable aircraft and operational crews at their disposal:
|Establishment||Strength||Serviceable||Total||Fully Trained||Partly Trained|
the finishing touches were put to plans for trade-defence and maritime reconnaissance. If physical resources dictated the extent to which shortages of vessels, aircraft and equipment could be made good, at least the crisis ensured that the deficiencies which it revealed would not be overlooked. By the beginning of September 1939, the strength of Coastal Command had risen to nineteen squadrons (including three torpedo-bomber squadrons), of which sixteen were fit for active service. Apart from the limited range of the Anson, a weakness of the general-reconnaissance squadrons was their lack of an effective means of sinking any submarines they might detect. Meanwhile the Admiralty had done their best to ensure that in 1939 shortages of escort vessels, minesweepers and the like—though in the outcome serious enough—would be less glaring than in 1938.
Among shortcomings not revealed by the crisis, one of the most notable was in the provision made for taking and interpreting air photographs as a source of information about the enemy’s dispositions and intentions. In general, air photography was regarded as a normal function of bomber and general-reconnaissance squadrons; and the difficulty which such squadrons would have in photographing hostile territory in time of war was underestimated.14 Ultimately the problem was solved by equipping a special Photographic Reconnaissance Unit (formerly the Photographic Development Unit) with fast, high-flying aircraft of fighter type. The ancestor of the unit was a small and highly secret flight set up for a special purpose in the early part of 1939, when its flying personnel comprised two pilots. Again, by the summer of 1939 both Bomber Command and the Air Ministry had staffs for the interpretation of air photographs—a task performed until the spring of 1938 exclusively by the army. But they proved incapable of getting the best out of the relatively small-scale photographs taken from great altitudes by high-performance aircraft.15 A commercial firm, the Aircraft Operating Company Limited, was able to fill the gap, and after the outbreak of war the solution was found in a forced marriage between service and civilian experts. Thus a window was opened on German preparations for invasion—and much else besides—in time for the events of 1940.
Where the air defences were concerned the lesson of the crisis was unmistakable, especially at a time when a ‘knock-out blow’ seemed likely to be attempted at the beginning of a war, and perhaps before war was declared. Whether the Air Staff were right or wrong in thinking that the bomber force could make a useful contribution to defence in the first few years of war, it would have no chance of doing so if the defences proper were too weak to avert defeat before a counter-blow could be delivered.
Accordingly in the autumn of 1938 Sir Kingsley Wood, who in May had succeeded Lord Swinton as Secretary of State for Air,
announced, with the approval and on the advice of the Minister for Co-ordination of Defence, that henceforth priority would go to fighters.16 Additional aircraft were needed both to strengthen the first line and to provide against losses to be expected at the outset. The new policy was reflected in Scheme M, which followed (but did not supersede) Scheme L in November. The scheme aimed at a metropolitan air force of fifty fighter and eighty-five bomber squadrons, the ratio of fighters to bombers thus rising from roughly 1:2 to 1:1.7. At the same time the hitting-power of the bomber force would be increased by equipment throughout with heavy bombers.* But Scheme M was intended for completion in 1942, when faster fighters and bigger bombers than those now coming into service could be expected. Meanwhile the aim was to build a fighter force which would be ready for action by the spring of 1939, and twelve months later would be backed by strong reserves. Its main strength would lie in the Spitfire and the Hurricane, whose good performance and eight-gun armament promised excellent results against the virtually unarmoured and lightly-armed German bombers then in view. Much was expected, too, of the Defiant, a new two-seater single-engined monoplane which ultimately proved disappointing.
But equipment of the entire fighter force with Hurricanes and Spitfires was not feasible, for it would have absorbed the whole output of those aircraft and have left no margin for reserves. As a makeshift measure the Air Ministry decided, therefore, to adapt a number of Blenheim bombers as fighters and equip at least three and possibly ten squadrons with them. The Blenheim was chosen not so much on merits as because it was one of the two types produced in the shadow factories, and was therefore available in substantial numbers. Yet it was by no means a bad choice, especially as it provided experience which proved invaluable when more advanced twin-engined aircraft came into service as night-fighters. Fighter Command was also strengthened during the last year of peace by transfer and re-equipment of a number of Auxiliary squadrons formerly in Bomber Command—a process begun on a much smaller scale some years before.
* The new programme (with Scheme L for comparison) was:
|Scheme L||Scheme M|
|Squadrons||First Line||Squadrons||First Line|
|METROPOLITAN AIR FORCE|
In the outcome the Auxiliary fighter squadrons, recruited mainly in large towns and cities, proved strikingly successful.
Two further reforms were the creation of an organisation for the salvage and repair of damaged aircraft, and the establishment of Group Pools (later called Operational Training Units) whose task was to relieve first-line squadrons of part of the burden of preparing qualified but untried pilots for active service, and to provide a reservoir from which casualties could be replaced. Six repair depots were set up in various parts of the United Kingdom, so that aircraft requiring major overhaul or reconstruction no longer had to be returned to the manufacturer. The first Group Pool in Fighter Command began to function in the spring of 1939.
The new sense of urgency created by the Munich crisis was felt throughout the country and not least in the aircraft factories. Output of Hurricanes and Spitfires rose sharply towards the end of 1938 and in the early part of 1939, when it exceeded the predicted figure by about a quarter.17 By the summer of 1939 a reserve of two hundred modern fighters had been assembled—a number insufficient to dispel anxiety, but one which held out some hope that before long the gap between resources and probable wastage might be bridged. By that time about the same number of Volunteer Reserve pilots had completed their flying training, although they still had to go through the Group Pool or its equivalent before they would be fit for active service. In the sphere of passive defence, too, good progress was made, especially after the appointment of Sir John Anderson as-Lord Privy Seal and, in effect, full-time Minister for Civil Defence.18 Before the crisis half a million citizens had volunteered as air-raid wardens and the like; in the next few months the number doubled. About thirty-five million respirators distributed to civilians in September 1938, were left in their hands and checked by a series of house-to-house visits, since to call them in would have meant depriving the public of them for six months while they were being overhauled and disinfected.19 Again, by the spring of 1939, 570 heavy anti-aircraft guns and nearly 2,000 searchlights were ready for deployment within two days —a considerable improvement over the numbers available six months before. On the other hand, the communications needed for the safe working of the air defence system in time of war were by no means complete, only about two-thirds of the planned radar stations and Observer Groups were ready, and shortages of trained operators and satisfactory equipment would still have hampered deployment of the London balloon-barrage if war had come in the spring or early summer.
Meanwhile new factors had carried demands on the air defences beyond even the ‘ideal’ plan of 1937. In the spring of 1939 the Admiralty informed the Home Defence Committee of their intention
to use both Scapa Flow and Rosyth as bases for the Home Fleet when war broke out.20 According to the accepted view, the fleet was capable of defending itself against air attack, whether in harbour or at sea; but the tankers, store-ships and other facilities on which its efficiency depended were not so fortunate. Hence the experts estimated that twenty-four heavy anti-aircraft guns would be needed for the defence of Scapa in place of the eight previously allotted to it as a ‘naval port of secondary importance’; and a plan was made to station two home-defence fighter squadrons at Wick, on the mainland about fifteen miles distant. Pending the planned extension of the radar chain to the Orkneys, a temporary OH. station was moved there from Ravenscar in Yorkshire. A fighter squadron and twenty-four guns were allotted to Belfast. These changes, with others which included plans for a mobile reserve of heavy guns and a reduction in the number of searchlights, brought the approved programme to that shown in the second column below.21
|‘Ideal’ Plan||1939 Plan|
|Fighter squadrons||45||* 53|
|Light guns (barrels)||–||† 2,000|
Of the balloons, 450 were for London and the remaining thousand for provincial barrages. Of the heavy guns, 168 were allotted to a mobile pool, the same number to a strategic reserve and 128 to aerodromes, leaving 1,768 to be divided between London, the leading industrial centres and the chief ports. The number allotted to London and the Thames and Medway defended area on its eastern outskirts was 480, or rather more than a quarter of that figure. Elsewhere the most heavily defended areas were to be Birmingham; the Mersey; the Forth; the Tyne, Tees and Sunderland; Portsmouth and Southampton; the Humber and Grimsby; and Glasgow with its outskirts. Nearly a third of the light guns were allotted to mobile and new requirements reserves, the rest divided in various proportions between factories and other civil objectives, naval, army and air force establishments (aerodromes claiming a big share) and railway junctions. Allotments of light guns were largely academic, since nothing like the number of pieces involved seemed likely to be available for several years.
To the allotment of the fighter squadrons we must now turn.
* Excludes the 4 trade-protection squadrons approved in August 1939.
† Includes 140 allotted to a War and Maintenance Reserve, leaving a net figure of 1,860 for Air Defence of Great Britain.
The problem of the hypothetical Expeditionary Force and its concomitants impinged at several points on those of home defence. On the one hand a strong force in France or the Low Countries might, and probably would, contribute substantially to the safety of the United Kingdom; on the other, units sent there would be drawn, at least in the first instance, from those otherwise available at home. For the army the issue was comparatively simple, since invasion was held to be unlikely. Hence presumably a large number of well-equipped divisions would not be needed at home in any case. For the air force the problem was more complex. Successive Air Expansion Schemes provided Army Co-operation squadrons for tactical reconnaissance, and did not exclude the despatch of other squadrons across the Channel for purposes which might include support to troops. The fact remained that any fighter or bomber squadrons assigned to the support of an army on the Continent would diminish the number available at home for pure defence or for ‘strategic’ bombing.
Until the spring of 1939 the Government were reluctant to commit the country to a land war in Europe, and accordingly refused to sanction unrestricted staff talks with Continental powers. In April 1938, they agreed, however, to ‘low level’ conversations between British and French officers, primarily for the purpose of exchanging information about air matters.22 In deference to French wishes, they conceded that naval topics and the possibility of sending an Expeditionary Force to France should not be excluded, on condition that the talks did not take place at a higher level than that of the service attaches. The outcome was a tentative plan for the despatch of two infantry divisions and an Advanced Air Striking Force of either ten or twenty bomber squadrons. The role of the bombers would be a ‘strategic’ offensive against Germany, rather than direct support for the still hypothetical two divisions.
Soon afterwards the virtual loss of some thirty Czech divisions in consequence of the Munich Agreement left France unwilling to bear the brunt of a war on land unless assured that a substantial British army would cross the Channel as soon as hostilities began. Should France collapse, or fall out for lack of such support, a British strategy based on access to the Channel ports and French aerodromes would have to be discarded. During the next few months the case for ‘full-dress’ staff talks thus became extremely strong. It was further strengthened in March 1939, when German troops crossed the frontier of the diminished Czechoslovakia under cover of a demonstration by the German air force over Prague.
Accordingly a new series of talks, conducted on the British side by
the Joint Planning Sub-Committee of the Chiefs of Staff Committee, and later by the Permanent Military Advisers (Designate) to the projected Franco-British Supreme War Council, began in London on 29th March.23 In due course the delegates agreed that four British divisions, instead of the two first proposed, should go to France as soon as war began, and that if Germany invaded the Low Countries ‘collaboration with the French Army and Air Force in the land battle’ should become ‘the primary commitment of the British Bomber Command during any critical phase of the invasion’. The Advanced Air Striking Force would now consist of a First Echelon of ten medium-bomber squadrons (equipped with Battles) and a Second Echelon comprising the same number of Blenheim squadrons. Later the plan for a Second Echelon was cancelled in favour of operations by the Blenheims from bases in the United Kingdom. Apart from the Advanced Air Striking Force—originally conceived as an outpost of Bomber Command rather than an army support weapon—the Expeditionary Force would be accompanied by an Air Component comprising eight Army Co-operation (reconnaissance) squadrons and four squadrons of fighters. Originally the last were to have been Blenheim squadrons; but largely in consequence of a memorandum by Air Chief Marshal Dowding, which stressed the need for speed and climbing-power in a battlefield fighter, the Air Staff ultimately decided to send Hurricanes instead. As they would necessarily be drawn from his command, the author of the memorandum was thus faced, as the result of his own candour, with the loss of four of his best squadrons. Worse still, he would lose the aircraft likely to be needed to keep them up to strength at a time when heavy casualties might well be suffered.
Hence the employment envisaged for the fifty-seven fighter squadrons contemplated in the final peacetime plan was:
|Air Defence (main scheme)||46|
|Defence of Scapa Flow||2|
|Defence of Northern Ireland||1|
The number of squadrons allotted to the air defence scheme proper—for Scapa and Belfast were outposts—thus corresponded very closely with that recommended in the ‘ideal’ plan of 1937. Moreover, it was precisely that at which the Air Staff had arrived in 1938 by a calculation based on the probable striking power of the German air force and the theoretical chances of successful interception.24 There was accordingly a strong case for regarding it in 1939 as the essential minimum. On the other hand, the allowance of four
squadrons for the Expeditionary Force was far from generous. Both the French authorities and the British General Staff pressed for more fighters, the latter suggesting that at any rate the number should be increased within the first six months of war. On the ground that the country was still short of the standard required for protection against a ‘knock-out blow’, the Air Staff refused to commit themselves to more than the four squadrons, but promised that all of them (instead of only one, as had been contemplated earlier) should cross the Channel with the first contingent of the Expeditionary Force, and that the possibility of sending others should be reviewed if no heavy air attacks were made on the United Kingdom early in the war.
The seizure of Bohemia and Moravia in March 1939, showed clearly that the German Chancellor had no intention of abiding by the agreement made at Munich, and that his claim to be concerned solely with areas inhabited by German-speaking peoples could not be relied on. The British Government responded by joining the French in guarantees to Poland; taking measures to bring the twelve divisions of the Territorial Army up to strength and then double them; introducing conscription; and setting up a Ministry of Supply to find the weapons needed by a rapidly expanding army.*25
Thereafter the home defences passed gradually from their peacetime state to one of readiness for war. Under a system of ‘couverture’ adopted in the early summer, anti-aircraft formations of the Territorial Army were called out in four contingents for one month at a time; guns were moved to prepared positions in a belt twenty-five miles deep extending from Newcastle to Plymouth. At the same time the radar chain was brought into operation. The public air-raid warning system was made ready for instant action, and the Postmaster-General placed essential telephone lines at the disposal of the air defences. Air Chief Marshal Dowding was given power to intercept unauthorised flights over the United Kingdom, and throughout the summer a continuous watch was kept by skeleton crews in the essential operations rooms of Fighter Command and its ancillary formations. In June, German aircraft began to make flights over the North Sea and the English Channel, but did not infringe British territorial limits and were not molested.26 The opportunity was taken to make important technical modifications to the radar system and order the ‘chain home low-flying’ (C.H.L.) equipment needed to detect and track low-flying aircraft.
* On paper there were thirteen Territorial divisions: in practice the number never exceeded twelve, or twenty-four when doubled.
In consequence the final transition to a state of hostilities was accomplished with fewer pains than the emergency deployment of 1938, and found the air defences in much better shape. Fighter Command mobilised thirty-nine fighter squadrons, as compared with the twenty-nine considered mobilisable eleven months before. Sixteen were equipped with Hurricanes, ten with Spitfires, seven with Blenheims, four with Gladiators and only two with the obsolescent Hind and Gauntlet. Reserves amounted to some 300 aircraft.27 After deduction of four squadrons for the Air Component, Fighter Command thus had thirty-five squadrons towards the forty-six approved for the main scheme of home defence, but none for Scapa Flow or Northern Ireland, and none as yet for trade-protection.* Anti-Aircraft Command, recently reorganised in seven divisions under Lieutenant-General Sir Frederick Pile, Bt. (but like the rest of the air defences under the operational control of Air Chief Marshal Dowding), mustered about one third of the heavy, one-eighth of the light antiaircraft guns and rather less than three-quarters of the searchlights to which it was entitled. Balloon Command (Air Vice-Marshal O. T. Boyd) deployed 444 balloons in London, and 180 elsewhere, on the first day of the war, or altogether about three-sevenths of its establishment.† The Observer Corps (Air Commodore A. D. Warrington-Morris) was virtually complete over the greater part of England and parts of Scotland, while the radar chain had all twenty of its C.H stations in action, though their equipment was still imperfect. No C.H.L. stations were yet ready.
As war became more probable, corresponding precautions were taken in other branches of home defence. In the course of the summer a number of naval reservists were called out by individual notice. In August a series of exercises was held to test naval and air plans for the detection of surface raiders and the laying of the mine barrage at the southern exit from the North Sea. Before the exercises the Reserve Fleet was held fully manned and was inspected by H.M. the King in Weymouth Bay. As they were drawing to a close, news that Germany and Russia were about to conclude a pact of non-aggression brought the threat appreciably nearer. Thereupon arrangements were made
* See p. 72.
† The figures, as compared with the approved scales, were:
|Approved Scale||Deployed by outbreak of war|
|Fighter squadrons||* 46||35|
|Heavy guns||2,232||† 695|
|Light guns (barrels)||‡ 1,860||253|
* Main Scheme only.
† Of which 425 were modern (4.5-inch and 3.7-inch) pieces.
‡ Excludes War and Maintenance Reserve.
to call out further reservists as they were needed, shipowners were warned of the dangers their vessels might run in foreign ports, and preliminary steps were taken to requisition shipping needed to carry the Expeditionary Force and the Air Striking Force to France. At the same time the Lord Privy Seal was authorised to put the Civil Defences on a war footing when he thought fit.
The signing of the Russo-German pact in Moscow on 23rd August was the signal for further measures, accompanied by a solemn warning to the German Government that Great Britain intended to stand by her pledge to Poland. Air reconnaissance over the North Sea began on the morning of the 24th; by the end of the month all ships of the Home Fleet and naval home commands—including nine capital ships, four aircraft carriers and seventeen cruisers—had moved or were moving to the war stations shown in Appendix I,28 and the sixteen active squadrons of Coastal Command were at the bases shown in Appendix 2. Anti-submarine booms were laid before the outbreak of war at Scapa Flow, Rosyth and Portsmouth, and arrangements were made to add the rest of the local naval defences in two days at the first two places and in nine days at the third.29 Elsewhere some risk of attack would have to be accepted while the schemes drawn up since 1933 were put in hand. The fixed defences were far from strong, for the 6-pounders considered best for defence against fast light surface craft were not yet ready; moreover most 9.2-inch and 6-inch batteries had nothing but an old type of ammunition whose replacement with a better kind had only just begun.30 But the deficiencies of the coast defences will be best considered in a latter chapter, where they can be studied in the light of events not yet foreseen.
A chart at Appendix 3 shows the broad structure of the organisation for home defence at the beginning of the war.