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Chapter 2: Disarmament and Rearmament, 1930–1938


Among reforms proposed by the Salisbury Committee in 1923 was an important change in relationship between the central administration and the professional heads of the three fighting services. The Chiefs of Staff, said the Committee, should not merely be advisers on questions of sea, land or air policy respectively, each answerable to his own Board or Council, but should have ‘an individual and collective responsibility for advising on defence policy as a whole, the three constituting, as it were, a Super-Chief of a War Staff in Commission’.1

The outcome was a new complex of sub-committees of the Committee of Imperial Defence, consisting in the first place of the Chiefs of Staff themselves, and secondly of a number of lesser bodies dealing with such aspects as planning and intelligence. In 1926 the Government defined the individual and collective responsibility of the Chiefs of Staff for tendering advice on matters of joint concern in a formal warrant given to each of them.2

Thereafter reports and memoranda submitted by the Chiefs of Staff to the Committee of Imperial Defence, both in their joint capacity and separately, drew a picture of weakness which grew more alarming as the international outlook darkened. At the beginning of the 1930s the army was smaller than in 1914 and was not organised for war in Europe—facts whose significance for home defence we have already noted.* Instead of being able to mobilise six infantry divisions and one cavalry division in less than three weeks, as in 1914, the War Office were in a position to mobilise within that time only one infantry division and one cavalry brigade.3 At sea the navy had a margin of strength over any likely enemy, but professional opinion held that the limit of fifty cruisers imposed by the London Naval Treaty of 1930 was twenty less than the smallest number needed to

* See p. 5.

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safeguard ocean trade.4 Moreover stocks of material for local naval defence had been pared so much in ten years of economy that a crisis overseas, could not have been met without denuding the home country.5 The coast defences, almost wholly neglected since the war, were so much out of date that there was not a port in the United Kingdom, nor indeed throughout the Empire, whose guns were not outranged by those of a modern six-inch cruiser.6 The air defences, as we have seen, were still a long way from completion, and the role of aircraft in maritime defence had yet to be determined.7

These facts were well known to the Government, but circumstances did not favour any radical reform. The country faced an economic and financial crisis which admittedly created a big reserve of labour, but which also made the measures needed to rearm the country appear untimely in the eyes of many statesmen of all parties. Moreover a large section of the public was undeniably opposed, on grounds which had little to do with finance or economy, to any move which smacked of war, and was not convinced that the best way to avoid war was to build up armaments.

There were also technical obstacles in the way of any large expansion of the defences, particularly in the air. Since the Armistice, progress in the art of air defence had been outstripped by the development of the bomber, so that even completion of the fifty-two squadron scheme and the complementary Romer Plan would not have made the country safe, especially as no probable enemy offered a target comparable with London. In 1918 General Ashmore had been able to put up fighters when approaching raiders crossed the coast, with some hope that they would intercept the enemy before he reached his target. But the speed of the bomber had doubled since that time and was likely to increase still further, so that nowadays the corresponding order must be given when the enemy was still some miles out to sea.8 Huge ‘acoustic mirrors’ made of concrete offered some hope of getting the necessary warning, but experiments at Hythe in Kent, where the building of a mirror two hundred feet in length was sanctioned, were disappointing. Many other measures were considered, including devices to detect the heat emitted by the engines of approaching aircraft, or the electrical effects created by their ignition-systems or by proximity to a magnetic field.9 All had grave defects. Unless the problem could be solved—and for some years no solution was in sight—the air defences would have no choice but to keep fighters on patrol whenever danger threatened. Such a course would quickly wear their squadrons to a standstill. Not knowing that the answer would be found within the next few years, Mr. Baldwin thus had reason on his side when he confessed in 1932 that ‘the bomber would always get through’.

Meanwhile, if the danger of air attack were real and could not be

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averted by naval power, the only action which seemed open to the Government was either to build a bomber force strong enough to deter aggression, or alternatively to strive for immunity by diplomatic means. The first course would be expensive and might entail the creation of an expeditionary force sufficiently numerous and well-equipped to hold or capture bases on the Continent. Moreover it might not achieve its object. The second promised to be cheaper, and might appeal more strongly to a public already heavily taxed and judged unlikely to support a major programme of rearmament. Furthermore, it had implications of special interest to a maritime country. By taking the lead in diplomatic action which removed the menace of the bomber, Great Britain would not only confer a benefit on humanity, but would also earn the reward of an honest broker if naval power again became the arbiter.

Accordingly, for reasons which may not have been solely idealistic although they certainly reflected a genuine preference for peaceful methods of adjustment, British statesmen worked hard during the next few years to secure a general scaling-down of armaments. At Geneva and elsewhere attempts were made to ban the bomber, or at least to bring about a drastic limitation of air power. As the Air Ministry were naturally reluctant to forgo a weapon in which the Air Staff had much faith, the views expressed by their spokesmen were not always easy to reconcile with those of other British delegates. But such divergences had little or no effect on the main issue. The banning of the bomber was defeated by the difficulty of devising any formula or course of action which would prevent an aggressor from dropping bombs from aircraft not defined as bombers.10 Similarly, abolition of military aircraft in general was dismissed on the ground that civil aircraft could be applied to warlike ends and could not be abolished or effectively controlled. After long discussion even limitation of size or numbers was rejected, no agreement on any major issue having been reached among the powers.11 Meanwhile little had been done to strengthen the national and Imperial defences, for British statesmen argued that any major measure of rearmament would be inappropriate while the negotiations were proceeding.


The country’s armaments, and not least the home defences, were thus in a poor state when the hope of a long peace began to fade. When the future of Singapore was discussed in 1925 the Foreign Secretary, Mr. Austen Chamberlain, had told the Committee of Imperial Defence that in his opinion any major clash in the Far East would be heralded by danger-signs in Europe.12 In the meantime Japanese ambitions in

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China, if they threatened British interests in that country, would also threaten those of the United States. By presenting a united front the two English-speaking powers should be able, in his view, to ensure that any action taken by Japan was not offensive to them.13

Five years later danger-signs in Europe were not lacking. At the general election held in Germany in the autumn of 1930 extremist parties of the Right and Left gained nearly a third of the votes cast. In the following spring the Chief of the Imperial General Staff, Sir George Milne, told the Committee of Imperial Defence that ‘nothing was clearer’ in the contemporary scene than the ‘gradual emergence of a revisionist bloc of powers consisting of the ex-enemy states and Italy.’14 In June the committee nevertheless reaffirmed the assumption that there would be no major war involving the British Empire for ten years.15 A few months later Japan began military operations in Manchuria and early in 1932 she attacked Shanghai. Resolute action to safeguard British interests there was found impossible without incurring a risk of war which the country could not face; and the common front predicted by Austen Chamberlain was limited to vain attempts by both the League of Nations and the United States to adjust the Sino-Japanese dispute by mediation.16

The principles which had governed British strategy for the last decade and more thus stood condemned by failure to avert a situation prejudicial to the country’s commercial interests in Shanghai and elsewhere in China. Moreover the ‘China incident’ had wider implications. Within a month of the crisis at Shanghai the Chiefs of Staff, referring ominously to ‘the writing on the wall’, called urgently on the Government to cancel the ‘ten-year rule’ and start providing for ‘purely defensive’ commitments without awaiting die results of the Disarmament Conference assembling at Geneva.17 Among the shortcomings to which they drew attention was the poor state of the home defences, including the weakness of the coast defences and the incompleteness of the scheme of air defence.18

The Government accepted the first recommendation, but were reluctant to apply the second as long as they retained the hope that international agreement might spare the country measures of rearmament which seemed to them financially and economically unacceptable. They nevertheless approved completion of the naval base at Singapore and its permanent defences by 1936, authorised certain naval and air measures designed to strengthen its position in the meantime, and appointed a committee under Mr. Baldwin to study the broad aspects of coast defence throughout the Empire.19 The chief effect on the home defences was the diversion of an air squadron to Singapore.

Soon afterwards events in Europe brought the danger nearer home. Early in 1933 the National Socialist Party led by Adolf Hitler came

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to power in Germany. On his own showing, Hitler was no enemy to Britain or the British Empire. He condemned the policy which had led his forerunners to challenge British naval power by seeking colonies across the sea, and pointed to the rich corn lands of European Russia as a proper field for expansion.* The goal could be attained, however, only by breaking through the ring of French alliances in Eastern Europe. Hence the course he seemed to favour was likely to bring him into conflict with France. Moreover, as the leader of a party with a strongly patriotic programme, he was logically committed to revisionist measures bound to be unacceptable to the French. Finally, some aspects of his domestic policy offended many foreigners who might not otherwise have been unsympathetic to German aspirations.

When Germany rejected the promise held out at Locarno by leaving the League of Nations, observers in Britain saw some reason to fear a conflict in which their country might become embroiled. Regarded as recently as 1931 by the General Staff as the dominant power whose excessive armaments kept Europe in a state of tension,20 France began to assume once more the guise of a hard-pressed neighbour who might need support against aggression, and who indeed might claim it under the terms of the Locarno Treaty. The Chiefs of Staff reminded the Government that cancellation of the ‘ten-year rule’ had not removed the deficiencies to which the rule had given rise, and warned them that postponement of rearmament might be disastrous if the Disarmament Conference failed to achieve its purpose.21 Accordingly the Cabinet, recognising that failure at Geneva was now inevitable, appointed in November 1933, a committee under their Secretary, Sir Maurice Hankey, to advise them how to meet ‘the worst deficiencies’ in national and Imperial defence.22


Meeting for the first time on 14th November 1933, the Defence Requirements Committee—whose members included the three Chiefs of Staff, the Secretary to the Treasury and the Permanent Under-Secretary of State for Foreign Affairs—took as their point of departure a recent dictum of the Committee of Imperial Defence that for the moment the chief danger lay in the Far East. Nevertheless they soon reached the conclusion that the ‘ultimate potential enemy’ was Germany.23 There was no evidence that Germany contemplated an attack on Britain or the British Empire, but plenty to show that she intended to pursue her aims without deferring to her neighbours. To

* Mein Kampf, Eng. Edtn. (1939), p. 533.

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what extent and in what circumstances Britain might consequently be called upon to honour her obligations under the Locarno Treaty was uncertain; but clearly the chances of an outcome which might put the country in jeopardy would increase as Germany rearmed. That she intended to rearm was plain. Accordingly the report submitted by the committee in February 1934, laid much emphasis on the importance of putting the United Kingdom in a thoroughly defensible condition.24

The General Staff believed that Germany might be ready for war by 1938 or 1939.25 Her navy seemed unlikely to become a serious threat within that time, but by concentrating on air power she might provide herself with a powerful offensive weapon. Aware that Germany had already begun to build an air force in defiance of the Treaty of Versailles, and perhaps influenced by Trenchard’s evidence before the Salisbury Committee in 1923, the Defence Requirements Committee drew attention to the risk of air attack ‘especially in the early stages of a war’. Like the ‘bolt from the blue’ which figured so much in discussions of defence plans before 1914, the newer conception of a ‘knock-out blow’ from the air at the very outset of a war owed more to speculation than to any evidence that the potential enemy contemplated such a move, but in course of time aroused much apprehension. Meanwhile the committee, although they urged completion of the fifty-two squadron scheme as a matter of ‘first importance’, themselves avoided any exaggerated reference to the danger. Recognising that the scheme (or more precisely the plan of air defence which it implied) would not protect the whole of the United Kingdom against attack from Germany, but mindful of their instructions to deal only with the ‘worst deficiencies’, they made no specific recommendation for a further increase in the home defence air force. They did, however, call attention to a probable demand for twenty-five additional squadrons for the defence of ports at home and abroad and for co-operation with the navy. They urged, too, that the public should be made acquainted with projected measures of passive air defence which had been studied in secret since 1925; suggested a moderate expenditure on coast defence and naval programmes, including local seaward defences against submarine attack; and recommended very strongly that a Field Force consisting of four infantry divisions, one cavalry division, two air defence brigades, one tank brigade and an air component drawn from the metropolitan air force should be made ready for despatch to the Continent within one month of the outbreak of hostilities. With such a force at its disposal the country would be able to co-operate with Continental powers in securing the Low Countries, where British bombers, fighters and observation posts could be deployed if they were needed there to ease the problem of defending London against air attack. The committee’s

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programme contemplated a capital expenditure of about seventy-one million pounds during the next five years; of that sum they proposed that roughly half should be devoted to the army, which had suffered most from recent economies.

The Government agreed that, for new reasons, the old principle of securing the Low Countries still held good; and in July a statement to that effect was made to the House of Commons by the Foreign Secretary. Examination of the Defence Requirements Committee’s proposals by a ministerial committee under the Prime Minister led, however, to the conclusion that the balanced force proposed by the former committee was beyond the nation’s mean’s.26 At the same time the Government were aware of a keen desire in the country for reassurance about the risk of air attack. They decided to reduce by about a third the capital expenditure proposed by their advisers, cut the army’s share by about a half, and rely largely on the deterrent effect of a larger air force than that suggested.

Meanwhile the Air Ministry had learned something of Germany’s intentions. According to their information, the German Government had adopted a ‘first-stage’ plan designed to give by the beginning of October 1935, a first-line strength of 576 aircraft, backed by adequate reserves and substantial provision for training.27 Thereafter the German air force would expand to 900 aircraft at the end of 1935, and would probably attain an ultimate strength of three or four divisions, each presumably about five hundred to six hundred aircraft strong. Further information digested in October and November indicated that the plan was being carried out, and that the second stage would give by the beginning of October 1936, a first-line strength of 1,368 aircraft.*28

To what extent the expansion of the Luftwaffe in its early stages kept pace with these projects the evidence which has reached us since the defeat of Germany does not clearly show. We know, however, that by the end of 1934 the Germans had formed, on paper, twenty-two of the forty-eight squadrons supposedly comprised in the first stage of their plan.29 The squadrons held 146 aircraft towards an establishment of 246.† The German Air Ministry’s total holding of military aircraft suitable for first-line units was 565, but many of these machines lacked engines or other necessary components.

To counter the first stage of the German plan and as much of Germany’s subsequent intentions as was known in the summer of 1934, the British Government adopted in July of that year a new

* The first-line strength of German squadrons was reckoned as 12 aircraft, a figure later reduced to 9 by excluding immediate reserves supposed not to be strictly part of the first line. The ‘second-stage’ total without immediate reserves thus became 1,026.

† The German establishment seems to have included some immediate reserves, and was thus not strictly comparable with first-line strength as defined by the British Air Staff.

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scheme of air expansion which replaced the fifty-two squadron scheme of 1923. Scheme A, as it was called, was designed to provide a metropolitan air force of forty-three bomber, twenty-eight fighter, four general-purpose (reconnaissance), four flying-boat and five Army Co-operation (tactical reconnaissance) squadrons by the end of 1938 or early in 1939.30 The numbers of first-line bombers and fighters contemplated in the respective schemes were thus as follows:

52-Squadron Scheme Scheme A
Bombers 394 500*
Fighters 204 336
598 836

In addition, 124 general-purpose, flying-boat and Army Co-operation machines included in Scheme A were reckoned as part of the metropolitan air force, whose total first-line strength would thus amount to 960 aircraft. The scheme provided also for 292 overseas aircraft in 27 squadrons. Hence the whole strength of the Royal Air Force would amount to 1,252 machines in 111 squadrons.

In principle, the great objection to Scheme A was that a threatened expansion of the British bomber and fighter force, unaccompanied by realistic preparations for war in Europe, would not necessarily persuade the Germans to forgo their ambitions. Indeed, it might induce them to hasten their preparations in the hope of striking while the ponderous mechanism of democracy was still gathering momentum. From a more immediate standpoint the chief weakness of the scheme was that it made inadequate provision for reserves.31 It allotted a small sum which would enable the air force to begin a war with something more than their bare first line, but deferred consideration of the bigger problem of keeping up the strength of the first line and the immediate reserve in a period of heavy fighting when losses were likely to exceed production. There was thus a grave risk that the potential enemy, by employing agents to discover how many machines the British aircraft industry was capable of producing and by calling arithmetic to his aid, might tumble to the fact that the Air Ministry’s goods were nearly all in the shop window.

Contemporary criticism was, however, directed largely to the size of the proposed force, as measured by first-line strength. Towards the end of November 1934, Mr. Winston Churchill attacked Scheme A in the House of Commons. He alleged that Germany already possessed an air force which was approaching equality with the British; that in twelve months’ time the Luftwaffe would be at least as strong,

* Includes 24 torpedo-bombers.

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and by the end of 1936 nearly half as strong again, as the Royal Air Force; and that by 1937 it would be almost twice the size of its competitor. Replying for the Government, Mr. Baldwin had no difficulty in showing that at any rate the first assertion was unfounded. He pointed out that, whereas the first-line strength of the Royal Air Force was 880 aircraft, of which 560 were at home, the Germans probably had from 600 to 1,000 military aircraft of all types. Whether they had yet formed any first-line units was uncertain. We have seen that five weeks later they had in fact formed a number of first-line units which were, however, very weak, and that they then had 565 machines of first-line type.* On the assumption that a number of trainers and other machines not of first-line type were entitled to rank as ‘military aircraft’, the figures quoted by Baldwin were well founded.

Turning to the future, Baldwin went on to say that in twelve months’ time the Royal Air Force would have a margin ‘in Europe alone’ of ‘nearly fifty per cent’, but that with respect to the more distant future he could make no forecast and that he could not look ‘more than two years ahead’. Perhaps because the speech to which he was replying had contained a specific reference to 1936, at least some of his hearers took him to mean that he could look two years ahead but no more. The debate continued on the assumption that he had predicted a safe margin of superiority in November 1936. Unfortunately he himself contributed to the misunderstanding, first by appearing to acquiesce in it at the time, secondly by avowing six months later that he had made a false prediction. The record shows, however, that his forecast was not ill-founded insofar as he intended to refer only to the position on 1st October 1935. Privately he complained afterwards that he had not been given full particulars of the second stage of the German plan.32 ln fact, the particulars were circulated to the Committee of Imperial Defence two days after he made his speech.33 But Baldwin had been warned at least as early as July that the expansion predicted for the period ending on 1st October 1935, was believed to be only the first stage of the German programme. Indeed, an appendix to a document which he himself signed on 16th July showed that, while the Royal Air Force would still have the advantage at the end of the first stage, subsequent expansion of the Luftwaffe would deprive them of it long before the end of the second stage was reached.34 Unhappily, in his attempt to meet Mr. Churchill’s criticisms, he failed first to distinguish between the respective positions on 1st October 1935, and at the end of that year, and secondly to rebut the presumption that he had predicted superiority in 1936.

* See p. 27.

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Meanwhile a new factor contributed to the confusion. Returning from a visit to Berlin in the early spring of 1935, Sir John Simon and Mr. Anthony Eden (respectively Foreign Secretary and Minister for League of Nations Affairs) informed their colleagues that the German Chancellor had told them in course of conversation that the Luftwaffe was already as strong as the Royal Air Force.35 The claim was certainly not justified. It was flatly contradicted by secret information in which the Air Ministry had confidence, and also by German officials, who at first denied that the Führer could have made so inaccurate a statement. But the Government’s faith in the Air Staff’s sources had been shaken by Mr. Churchill’s confident predictions and by the muddle arising from Baldwin’s speech. They therefore sought a further explanation through diplomatic channels. Under pressure, General Milch of the German Air Ministry conceded that the Führer had made a statement of the kind imputed to him, adding that he had had in mind a figure of some 800 or 850 aircraft but had intended only an approximate comparison.36 On 22nd May Milch’s superior, General Göring, made a similar avowal. He added that he hoped to achieve, perhaps by the end of 1935, a strength of 2,000 aircraft and consequent equality with France.37 The French air force was, however, known to be in the throes of a drastic reorganisation and seemed unlikely to reach within the next few months the strength assumed by Göring.38 For many reasons the British Air Staff came to the conclusion that, while Germany would doubtless muster 2,000 military machines and pilots by the end of the year, she would certainly not attain within that time a first-line strength of 2,000 aircraft as first-line strength was understood in London.39

Amidst many uncertainties one fact seemed to stand out clearly: namely that the announcement of Scheme A in the previous year had not induced the potential enemy to draw in his horns. The Luftwaffe might be expanding at the rate predicted by the Air Staff; alternatively it might, as Mr. Churchill and some members of the Government feared, be expanding faster. Two lines of thought converged, however, to the conclusion that a first-line strength of roughly 1,500 aircraft would be reached in the spring of 1937.40 In the first place, parity with the French metropolitan and North African air force was an avowed and very credible German aim, and France was expected to reach about that number at that time.41 Secondly, circumstantial evidence relating to the German programme pointed to a figure of 1,512 aircraft as the target for the beginning of April in that year.42

Despite the apprehensions expressed by Government spokesmen in the early part of 1935, the threat summed up in June by the Air Parity Sub-Committee of the Ministerial Committee on Defence Requirements thus appeared to the Sub-Committee scarcely different

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from that foreseen in 1934.*43 The only real change was that the failure of Scheme A was now admitted. The Government had set out to frighten Germany, but so far seemed to have frightened no one but themselves and some of their compatriots.

Meanwhile they had marked their new appreciation of the threat by adopting, an accelerated programme of air expansion called Scheme C.44 Intended for completion in the spring of 1937, the new scheme raised the numbers of bomber and fighter squadrons at home to 70 and 35 respectively, and increased the ratio of medium and heavy to light bombers.† In other respects it was scarcely an improvement on its predecessor. Provision for reserves was again inadequate—a fact betrayed by the financial implications of the scheme. Moreover the air programme was not backed by convincing preparations for land warfare on the Continent. Thus the Germans might regard it—indeed there is some evidence that they did regard it45—partly as bluff and partly as a device to reassure the British public.


We have seen that Scheme A failed to stop the Germans from rearming, and that Scheme C threatened to be equally ineffective in that respect. As a means of defence against an attempted ‘knock-out blow’, the new scheme had still greater drawbacks. Two-thirds of the home defence force which it envisaged would consist of bombers, the remaining third of fighters. This ratio reflected accurately enough the Air Staff’s view that in the long run only offensive power could give the air superiority which made for safety. Against an aggressor who acted swiftly the bomber force would, however, be of little value if the fighter force and the rest of the air defences should prove too weak to repel a series of crushing blows at the outset of hostilities.

* See p. 27.

† The respective programmes under Schemes A and C were:

Scheme A Scheme C
Squadrons First Line Squadrons Second Line
Heavy bombers 8 80 20 240
Medium bombers 8 96 18 216
Light bombers 25 300 30 360
Torpedo bombers 2 24 2 24
Fighters 28 336 35 420
Reconnaissance, etc. 13 124 18 252
84 960 123 1,512
OVERSEAS 27 292 27 292
111 1,252 150 1,804
FLEET AIR ARM 16½ 213 16½ 213

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Moreover there was, to say the least, no certainty that the bomber force would be capable of effective action against the potential enemy. Two-sevenths of it was to be equipped with aircraft able to reach the Ruhr, but not Berlin, from British aerodromes; three-sevenths with light bombers unable to reach worth-while targets in Germany unless they flew from Continental bases. The remaining eighteen squadrons were to be equipped with aircraft of which no satisfactory type was yet available.46 The thirty-five fighter squadrons would have aircraft which ranked high by the standards of the day, but would be handicapped by the difficulty of spotting and tracking approaching forces in time to intercept them.*

Production of the aircraft envisaged in the scheme—including a new type to supply the existing lack of medium bombers—was thought to be within the capacity of manufacturers on the assumption that they either enlarged their factories or fulfilled no civil or foreign orders. Apart from the admitted difficulty of completing the programme within the time allotted, a great weakness from the professional aspect was the dependence of so much of the force on Continental bases which, for one reason or another, our squadrons might not be able to occupy before the enemy delivered his first blow.

These problems did not escape the Air Staff. In their conception of air warfare as largely a slogging match between rival bomber forces, they had always recognised the great importance of purely defensive measures in the early stages of a contest, when the initiative would lie with an aggressor. Hence a saving consequence of the ill-fated expansion schemes of 1934 and 1935 was the attention devoted to the defensive system of which the Steel-Bartholomew and Romer plans were prototypes.

The aim of the Romer plan was to guard London, and give some

* The aircraft contemplated were:

Type Normal Range (miles)
Hendon 920 (1,500 lb. bomb-load)
1,160 (1,000 lb. bomb-load)
Armstrong prototype (40 expected by 31.3.37) 1,250 (1,500 lb. bomb-load) (estimated)
Not selected Probably 700-800 miles (750-1,000 lb. bomb-load)
Hind 430 (500 lb. bomb-load)
Type Maximum Speed (m.p.h.)
Gauntlet 230
or Gloster prototype 255
(delivery expected to begin in 1936) (estimated)

Map 3: The Reorientation 
Scheme, (1935)

Map 3: The Reorientation Scheme, (1935)

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incidental protection to the Midlands, against attack from the south and south-east. Now that Germany was the potential enemy the likely direction of attack was from the east. Recognising that the defences must therefore be reorientated, the Air Staff examined various proposals and gave their verdict in favour of a continuous defence-zone stretching from the Tees round London to the Solent.47 A committee under Air Chief Marshal Sir Robert Brooke-Popham, since 1933 commanding Air Defence of Great Britain, was appointed to work out a new plan.

The Reorientation Committee reported early in 1935.48 They upheld the conception of a continuous defence-zone, preferably divided into two areas for the defence of northern and southern England respectively, and comprising an aircraft fighting zone, an outer artillery zone, and an inner artillery zone for the close defence of London. (See Map 3.) Local defences in the form of guns and searchlights should, in their opinion, be provided also for Manchester, Leeds, Sheffield and Birmingham, and ultimately should form part of the main system. Guns and searchlights at defended ports in front of the defence-zone or on its flanks, on the other hand, would remain outside the system, since Air Defence of Great Britain had as yet no responsibility for them. The Committee noted, however, that the intention of the War Office was to allot 88 guns and 174 searchlights for their defence. The principal measures contemplated in their report included fighters, searchlights, anti-aircraft guns, balloons, light automatics for use against low-flying aircraft, and such additional aids to safety as air raid precautions, camouflage, smokescreens and control of wireless transmissions likely to be useful to the enemy for navigation. Ancillary measures would include predictors, height-finders, sound-locators, the Observer Corps and other means of detecting and tracking hostile movements, and finally a comprehensive system of communications.

The numbers of fighter squadrons, anti-aircraft guns and searchlights needed for the new plan, as compared with those previously contemplated, were as follows:

Modified Romer Plan*

Reorientation Plan

Fighter squadrons 17 25†
Guns 218 456
Lights 624 2,160

* The Romer Plan as modified by the projected installation of searchlights in the outer artillery zone and by inclusion of the Thames and Medway defences.

† Under Scheme C a further ten would be available for deployment on the Continent. The intention was that four or five of them should support the Expeditionary Force if circumstances required it.

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Apart from fighter squadrons, which were adequately provided for in the air expansion schemes, the new plan thus involved a big additional demand for guns and lights. It would also entail much work on aerodromes and communications and a considerable expansion of the Observer Corps, now to be reorganised in sixteen groups instead of the eighteen smaller groups envisaged earlier. At best it would give no more than a moderate degree of safety, for the problem of early warning was still unsolved.

In principle, completion of the Reorientation Plan at the same rate as Scheme A—soon to be succeeded by Scheme C—was much to be desired. The Committee recognised, however, that financial limitations were likely to preclude that course. They therefore proposed that the work should be done in three stages. Stage i would build a framework for the raising and training of the army units needed for the full scheme, and for the formation of the necessary Observer Groups; meanwhile it would provide 136 guns and 1,008 searchlights, including 104 guns for London and the Thames and Medway, and would enable the southern part of the aircraft fighting zone, from Huntingdon to the Solent, to be carried almost to completion. Stage 2 would add 168 guns and provide an attenuated aircraft fighting zone from Huntingdon northward to the Tees. Stage 3 would complete the full scheme, including local provision for Manchester, Leeds, Sheffield and Birmingham. In the fight of the information furnished by Sir John Simon and Mr. Eden on their return from Berlin in the spring of 1935, the Home Defence Committee recommended that Stages 1 and 2 should be completed within the next five years and Stage 3 two years later, though they also made alternative proposals. The Air Staff, too, were much in favour of completion of the whole scheme by 1942.49

These recommendations were not accepted. In the summer of 1935 the Government sanctioned completion by the spring of 1940 of that part of Stage 1 which related to the southern portion of the aircraft fighting zone and the provision of 136 guns and 1,008 searchlights, but not the further steps which envisaged completion of the full scheme two years later.50 Financial stringency, and especially difficulty in obtaining sanction for expenditure on weapons not immediately contemplated in measures already approved, continued for some years to place obstacles in the way of those whose eyes were directed to the future.

The decision of 1935 was distasteful to the Air Ministry, who would have welcomed a less niggardly provision.51 But if the Government’s action seemed inconsistent with one aspect of their policy, it was quite consistent with another. Having decided not to spend much money on the army, they had good reason to suppose that the War Office would not be able by 1942 to raise, train and equip the Territorials

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needed for the full scheme.* The irony was that one of the Government’s motives for reducing the Defence Requirements Committee’s allocation to the army had been that they wanted to spend more on air defence. As it was, the air defence plan would be seriously out of balance. Under Scheme A the home defence air force would be ready by 1939, under Scheme C by 1937; but the complementary fighter sectors, guns and searchlights would be a long way from completion even at the later date.

Meanwhile the Government’s decisions to adopt Scheme C and a part of the Reorientation Plan, if somewhat contradictory, at least had the advantage of setting definite objectives. Perhaps for that reason they marked the beginning of an era of real progress.

Under Scheme C the home defence air force would rise to 70 bomber and 35 fighter squadrons. It would thus be too large to be commanded by one officer. The Air Staff had no doubt that ultimately bombers would become the country’s main shield against air attack, for in their view only offensive action from a well-guarded base could give the air superiority which would bring security. Even so there was a good case for divorcing immediate control of the bomber force from that of fighters, guns and searchlights. If the country were heavily attacked, and if the bomber force and the defences proper were under one commander, he might face an invidious choice between immediate reprisals against the opposing air force and some other course of action, such as attacks on factories or naval bases. Admittedly he could turn to his superiors for guidance; but the argument that a bomber commander without purely defensive responsibilities would be better placed to make a realistic choice within the framework of his instructions still held good. Moreover, we shall see that by the time the problem of command arose, technical advances promised to confer a new status on purely defensive measures.

Accordingly, within the next twelve months the command called Air Defence of Great Britain disappeared, although the name continued to be used occasionally as a convenient term for the functions exercised by the commander of the air defences proper in his dual relation to the fighter force and to the air defence formations provided by the army. It was replaced by Bomber Command, concerned entirely with bombers of the metropolitan air force, and Fighter Command, concerned not only with fighters, but also with other elements of pure air defence, including operational control of guns and searchlights. Training—other than the operational training then

* The authorised establishment of the Territorial Army in 1935 was 165,000 and the enlisted strength about 130,000. The number needed for the Reorientation Plan was 43,500. Besides acting as the main reserve behind the Expeditionary Force, the Territorials were the principal source of manpower for coast defence.

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done in squadrons—became the task of a new Training Command, which replaced the old Inland Area and was later divided into two commands concerned respectively with flying and technical instruction. In due course Coastal Command (replacing Coastal Area) and, later Maintenance, Balloon and Reserve Commands were added to the home commands.

The appointment of Air Chief Marshal Sir Hugh Dowding as the first Air Officer Commanding-in-Chief, Fighter Command, and the opening of his headquarters at Stanmore, in Middlesex, on 14th July 1936, marked the transition from an experimental stage to one of active preparation for an emergency which might not be long delayed. Apart from the recently-formed 1st A.A. Division (Major-General R. H. D. Tompson), which was under his operational control but not yet in a position to fight, the new commander’s resources when he took up his post comprised No. 11 (Fighter) Group (Air Vice-Marshal P. B. Joubert de la Ferte), with eight stations and eleven squadrons in south-east England; the Observer Corps (Air Commodore A. D. Warrington-Morris), with nine Observer Groups south of the Wash and two in Lincolnshire and Yorkshire; and (for administration only) No. 22 (Army Co-Operation) Group, whose task was to provide reconnaissance squadrons for the army. In addition a new Regular fighter squadron was about to form in Cambridgeshire, three Auxiliary squadrons were converting from bombers to fighters in Bomber Command, and five Regular squadrons in Egypt and Malta belonged in principle to the home defence force and in fact went under Fighter Command when they returned to England in September.

Meanwhile there had occurred the most important development yet recorded in the field of air defence. We have seen that, some years earlier, attempts to find a better means of detecting distant aircraft than was provided by sound-locators and acoustic mirrors had led to negative results. Early in 1935 Sir Robert Brooke-Popham’s Reorientation Committee recommended that the Anti-Aircraft Research Committee which had then examined the question should be revived, perhaps in a new form, ‘to give further consideration to possible means of defence’. About two months earlier Mr. H. E. Wimperis, Director of Scientific Research at the Air Ministry, had made a rather similar suggestion.52 His proposal was that a committee headed by Mr. H. T. Tizard, Chairman of the Aeronautical Research Committee, should be set up to investigate, amongst other matters, the chances of damaging the mechanism or detonating the bombs of an approaching aircraft by means long known to be feasible in theory, and popularly associated with the conception of a ‘death ray’. In the outcome both suggestions were adopted. The body proposed by Mr. Wimperis became known as the Committee for the Scientific Survey of Air

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Defence, that proposed by the Reorientation Committee as the Air Defence Research Committee. Mr. Tizard was a member of the second and chairman of the first.

In January 1935, Wimperis followed up his idea by consulting Mr. R. A. Watson-Watt of the National Physical Laboratory about the possibility of damaging approaching aircraft, or harming their occupants, by means of electro-magnetic radiations. Mr. Watson-Watt reported that such a method would not work. But he added that certain researches on which he was engaged suggested a novel means by which approaching aircraft, although they could not be directly destroyed or rendered harmless, might be detected and located. That radio waves were reflected by an ionized layer about sixty-five miles from the earth—the Heaviside layer or ionosphere—was well known. His researches were concerned with measuring the distance of the ionosphere from the surface of the earth by noting the interval between the emission of a radio pulse and the return of the corresponding echo.

At their first meeting on 28th January, the Committee for the Scientific Survey of Air Defence considered Watson-Watt’s idea and suggested that he should pursue it. The Committee thereupon arranged that the Air Member for Research and Development should be asked to seek approval for expenditure on the project. Air Marshal Dowding, who then held that post and was later to command the air defences, responded by asking for evidence that an aircraft would emulate the ionosphere by reflecting radio waves in the form of an appreciable echo.

Accordingly, Watson-Watt and his associates gave a practical demonstration on 26th February. Ideally a pulse transmitter was required, but as none was available a source of continuous radiation was used in the shape of the beam from Daventry radio station. An improvised receiver was set up some six miles away at Weedon. A Heyford aircraft flew backwards and forwards at a height of 6,000 feet between Daventry and a point twenty miles along the lateral centre of the beam, but did not keep directly over the lateral centre as was intended. Thus conditions for the demonstration were by no means perfect. One run was disappointing. To the immense relief of the demonstrators, easily discernible echoes were received on the other three at ranges up to eight miles.

After his visit to Weedon, Dowding took steps whose consequences were perhaps as decisive for his country as any event recorded in British history. On his recommendation permission was obtained to spend more than the sum first proposed, and an experimental station was set up at Orfordness, on the Suffolk coast.

Immediate results were extremely promising. When the apparatus at Orfordness was demonstrated to the Secretary of the Committee

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for the Scientific Survey of Air Defence in July, a Bristol aircraft which flew thence to Bircham Newton was easily detected at distances up to twenty-five miles. Observers accustomed to the apparatus could see echoes at distances up to thirty-five or forty miles and could assess range fairly accurately from five miles upward. Echoes were also given by aircraft not concerned in the demonstration, so that their occupants could not be suspected by the most sceptical of conniving at its success.

During the second half of 1935 progress was again good. In the course of the year work on acoustic mirrors was stopped, and sanction was obtained for the construction within the next six months of five detecting stations north and south of the Thames Estuary. They were intended as the first instalment of a chain of about twenty covering the coast from the Tyne to Southampton. As the stations would all stand on high ground near the sea, and be furnished with conspicuous masts about 250 feet tall, their existence could not be concealed; to balk enquiry they were, however, given the misleading name of Radio Direction Finding Stations. The abbreviation R.D.F. remained in use until the middle of the war, when the now familiar ‘radar’ was adopted. A property on the Suffolk coast, called Bawdsey Manor, was bought to serve as an experimental station and headquarters of the chain. At the beginning of August 1936, Mr. Watson-Watt left the National Physical Laboratory to become full-time Superintendent of Bawdsey under the Air Ministry.

In practice, construction of the stations took longer than had been expected. Erection of the masts proved a slow job, and other setbacks were experienced. An ambitious programme of exercises arranged for the autumn of 1936 had to be postponed because the stations were not ready. A more modest trial held in the meantime showed that if accurate indications of range, height, bearing and approximate numerical strength were wanted—and all these were necessary if full value was to be had from the project—the organisation must be given time to find its feet. By the summer of 1937 the position was that, while the usefulness of the apparatus had been clearly demonstrated, only one station was in satisfactory working order. The Air Ministry foresaw that, if they awaited completion of the other four comprised in the first batch before continuing with the fifteen still to be erected, the chain would certainly not be ready before the spring of 1940. With the approval of the Treasury, they decided therefore to proceed at once with the whole system, now recast to cover the coast from a point north of St. Andrews to St. Catherine’s Point. In the meantime completion of the first five stations would be hastened so that they, at least, would be ready by 1938. Orders for the necessary transmitters, receivers and goniometers were placed with the Metropolitan-Vickers Electrical Company Limited, A. C. Cossor Limited and the Radio

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Transmission Equipment Company Limited, respectively. Meanwhile the Air Staff and Fighter Command—the latter now under Dowding—had shown their faith in the ultimate success of the venture by concerting a system of fighter control designed to use the information furnished by the stations. An important step was the appointment, towards the end of 1936, of Squadron Leader R. G. Hart, a signals officer attached to No. 11 Group, as Commandant of R.D.F. Training. The assumption made in the summer of 1937 was that the twenty ‘chain home’ (C.H.) stations, when complete, would be capable of detecting and locating at ranges up to forty miles all aircraft approaching the coast between Lowestoft and St. Catherine’s Point at heights above 3,000 feet. North of Lowestoft a lower standard would suffice, except in the neighbourhood of a few ports where the full standard was required. Later the equipment was much improved and substantially longer ranges became common. A weakness of the C.H. stations was, however, their inability to spot low-flying aircraft.

But the C.H. stations did not exhaust the scope of the project. As early as the summer of 1935 the few who shared the secret of R.D.F. foresaw a number of other uses. Research and experiment soon showed that special applications might include short-range location for the benefit of anti-aircraft gunners, searchlight crews and fighter-pilots. Warships, too, might profit by long-range detection and location of surface craft, while short-range location would increase the chances of naval anti-aircraft gunners. Coast defence was yet another application. Accordingly, all three fighting services were soon associated with the venture. The Admiralty appointed a scientist, Dr. A. B. Wood, to keep the Naval Signal School at Portsmouth in touch with the experiments; and a visit to Bawdsey by Dr. E. T. Paris of the War Office Air Defence Establishment at Biggin Hill in February 1936, was followed by the attachment of Dr. Paris and a small staff to cooperate with Mr. Watson-Watt and his associates. Within the next few years the development by Dr. Paris and his assistants of equipment suitable for coast defence pointed the way to a solution of the problem of tracking aircraft which flew too low to be spotted by the ordinary C.H. stations.

There were, however, many difficulties tending to oppose a simultaneous advance along a number of divergent lines. Although much was common ground, each field of application raised technical problems peculiar to itself; and all demands could not be met by making one kind of equipment. The supply of specialists, facilities for experiment, and manufacturing resources were all limited by complex factors, of which the need for secrecy—important as it was—was only one. Accordingly some uses took precedence over others. Inevitably, first place went to the C.H. stations, not merely because they

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had been first thought of, but also for the much better reason that long-range detection and location of aircraft offered the best chance of meeting the massed air attacks with which war seemed likely to begin. If measures particularly applicable to night air defence progressed more slowly, the reason was not solely that the need for them seemed less urgent, but also that they threatened to take longer to perfect. Other applications ranked still lower. But here, too, the working policy adopted in the period of evolution, rough and ready though it may have been, was broadly justified by subsequent events.

By 1938 the administrative burden thrown on Mr. Watson-Watt, or in his absence on Dr. Paris, had become so heavy as to call for changes which culminated in the establishment of a special directorate of the Air Ministry to supervise the project. Watson-Watt moved to the Air Ministry as head of the new organisation and was replaced at Bawdsey by Mr. A. P. Rowe, who had recently been added to the staff as Deputy Superintendent. Soon afterwards an inter-service Committee was set up to deal, amongst other matters, with the allotment of priorities for research, development and production. Until that time these difficult questions were settled largely on the direct advice of the small band of experts who alone had sufficient knowledge to weigh the issues. We have seen that, broadly, their policy was to put long-range detection and location of aircraft first. Consequently, as we shall see in later chapters, the C.H. stations were ready when the moment came, but a number of devices needed to counter the night bomber reached maturity too late to achieve much when they were most needed. Inevitably, that outcome led to some repinings. But on the assumption that a choice had to be made, the course adopted was certainly the right one. Had the decision been reversed—had completion of the C.H. stations been deferred while other and more complex devices were developed—it is as certain as such hypotheses can ever be that the Battle of Britain and perhaps the whole war would have been lost. It may be argued that the need for a choice ought not to have arisen. To find enough resources, and especially enough trained researchers, to pursue all lines of development at once would, however, have been extremely difficult even if money and foresight had been unlimited. In any case, the progress made during the sixty-six months which divided Watson-Watt’s discovery from the beginning of heavy air attacks on the United Kingdom remains a feat that reflects much credit not only on those directly engaged in the experiments, but also on others who saw their value and made sure that funds were provided for them. Among those others was Lord Swinton, whom the need for secrecy debarred from publicly receiving credit for his foresight at the time of his resignation from the post of Secretary of State for Air in 1938.

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In the meantime much had happened to show that a discovery which promised to revolutionise the possibilities of air defence had come none too soon. In the autumn of 1935 tension between Great Britain and Italy, arising from Italian aggression against Abyssinia, caused such alarm that the Government felt bound to take steps for the protection of Alexandria and Malta. Troops, ships, air forces and equipment were despatched there in such numbers as seriously to threaten security at home. Most of the anti-aircraft ammunition intended for home defence was shipped abroad; with it went nearly all the material normally available for the local seaward protection of home ports.53 The ability of the home defences to cope with a sudden threat was thus reduced to a level which, if the facts had become known, would have appalled the public, and perhaps not least those members of it who were most critical of the Government’s rearmament proposals. Germany, too, showed no sign that Scheme C had induced her to modify her aims. The ‘revisionist bloc’ predicted in 1931 was now in being, and was growing daily stronger and more belligerent.

At the beginning of 1936 the hope that peace might yet be saved was strong. On the other hand, the likelihood that the air force and the Field Force might have to be used in war, not merely as weapons of diplomacy, was clearly greater than in 1934. The Government remained reluctant to commit the country to a long war on the Continent; but where the air force was concerned they applied the lesson. In February they sanctioned a new scheme of air expansion, far superior to those they had adopted earlier.54 As compared with Scheme C, Scheme F strengthened the first line of the home defence force only by substituting medium for light bombers and by minor changes in other fields, but had the great merit of making good provision for reserves.* To provide the necessary aircraft, the Government decided to apply forthwith—instead of waiting until the outbreak of war, as they had at first intended—a scheme for the production of aircraft and aero-engines in ‘shadow factories’ organised by some of the leading manufacturers of motor-cars. The types selected were Fairey Battle single-engined and Bristol Blenheim twin-engined bombers, and the Bristol Mercury VIII air-cooled engine. They were chosen because they promised to be comparatively easy to produce, but in other respects the first was not a happy choice. Whatever its merits when first designed, by 1936 the Battle had only a doubtful place in the front rank of medium bombers. A subsequent impression that the

* See footnote on p. 42.

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specification—for which the Air Staff, not the designer, were of course responsible—was not a good one proved well founded in 1940, when squadrons equipped with the Battle suffered heavy casualties in France. The Blenheim, on the other hand, made a useful contribution in the early stages of the war, both in its original form and as a stopgap long-range fighter. In general, Scheme F was a sound one, infinitely preferable to its predecessor, since it aimed at real strength in 1939 rather than a hollow pretence of strength in 1937.

Moreover, a great change was coming over the design of military aircraft, so that far better fighters and bombers than any yet in service were on the way. The fighters of 1936 were the Bristol Bulldog, the Gloster Gauntlet, the Hawker Demon and the Hawker Hart. All were biplanes, as was the newer Gloster Gladiator. In four or five years all except the Gladiator were to seem nearly as outmoded as the penny-farthing bicycle. But in 1934 the Air Ministry had drawn up two specifications—modified in 1935—which contemplated a far higher standard of performance. While these specifications were in preparation Mr. R. T. Mitchell and Mr. Sidney Camm, employed respectively by Supermarine Limited and Hawker Aircraft Limited, had designed monoplane fighters—later called the Spitfire and the Hurricane—which reflected experience gained in the international Schneider Trophy contests and which embodied just those features now seen to be most desirable. In the spring of 1935 an officer from the Air Ministry, Squadron Leader R. S. Sorley, inspected ‘mock-up’ versions of both aircraft. He was so much impressed that he urged his superiors not to wait for the prototypes to be completed and tested

* The programme (with the Scheme C programme for comparison) was:

Scheme C Scheme F
Squadrons First Line Squadrons First Line
Heavy bombers 20 240 20 240
Medium bombers 18 216 48 750
Light bombers 30 360
Torpedo bombers 2 24 2 32
Fighters 35 420 30 420
Reconnaissance, etc. 18 252 24 294
123 1,512 124 1,736
OVERSEAS 27 292 37 468
150 1,804 161 2,204
FLEET AIR ARM 16½ 213 *26 *312
RESERVES £1,200,000 to provide immediate reserve £50,000,000 to bring total reserves up to 225 per cent. of first-line strength
Date for completion 31.3.37 31-3-39

* Rising by 1942 to 40 squadrons, 504 aircraft.

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before taking steps which would enable production to be started without delay and delivery to squadrons to begin next year. For reasons which seemed good at the time, the suggestion was not adopted; accordingly, a few Hurricanes and Spitfires took part in the fly-past of new aircraft at the Hendon Display in 1936, but the machines did not appear in squadrons until some two years later, and then only in numbers too small to affect the diplomatic struggle that led to Munich. Squadron Leader Sorley was, however, successful in urging that the new fighters should carry eight guns apiece instead of four. The specification met by the four-engined Short Stirling bomber was drawn up in the spring of 1936 and was followed by another on which were based the Avro Manchester (followed by the Lancaster) and the Handley-Page Halifax. Production of the Manchester, Stirling and Halifax began in earnest during the winter of 1938–39, although the machines did not go into active service until the early part of 1941.

In order to match the contemplated reserve of aircraft with a sufficiency of pilots, the Air Ministry obtained sanction in the summer of 1936 for the formation of a new body called the Royal Air Force Volunteer Reserve. Training of reservists began in the spring of 1937. At that time the establishment of the Regular Air Force, filled largely by short-service entrants, stood at 55,000 officers and men. The Regular establishment was backed by a small but enthusiastic Auxiliary Air Force, corresponding to the Territorial Army. Created in 1924, the Auxiliary Force had since absorbed the Special Reserve, set up in the same year and akin to the Militia.

The years from 1935 to 1937 were also notable for much-increased demands on the static elements of air defence. At the same time technical developments called for changes in their deployment.

In 1935 the Reorientation Committee necessarily based their recommendations on the same broad principles as had guided their forerunners. Thus they took over the main features of the Steel-Bartholomew and Romer plans, including the outer artillery zone. Soon afterwards the coming of radar promised to extend the aircraft fighting zone to the coast and even out to sea. Henceforth there would be neither room nor urgent need for an artillery zone* in front of it, although locally-defended areas would still be necessary at certain ports. Accordingly, in 1936 the outer artillery zone was abolished and its guns were freed for use elsewhere. The saving thus effected, was, however, more than offset by other requirements which soon compelled the War Office to enlarge their programme. Moreover, as the threat of war with Germany took shape, the need was felt for a more effective means of defence against low-flying aircraft than was

* See Map 3.

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provided by the light automatic weapons already contemplated.* Apart from something in the nature of a two-pounder, which would certainly be required in the long run, balloons might make a useful contribution.

In the First World War balloon-aprons had been used for the defence of London, but their value was debatable. After the Armistice the prevailing opinion was that only balloons capable of lifting a stout cable which would almost certainly destroy an aircraft that collided with it were worth having. By 1936 many years of experiment had convinced the Air Staff that there was no immediate prospect of perfecting a balloon capable of taking such a cable to the 15,000 feet or more at which high-level bombers would fly in a future war.55 On the other hand, low-altitude balloons capable of flying at 5,000 feet, and thus seriously hampering or even preventing low-level bombing, were quite feasible. Accordingly, in the summer of that year the Committee of Imperial Defence approved the suggestion that a barrage comprising 450 balloons should be installed for the defence of London.56 We shall see that, by the time the London barrage became an accomplished fact, demands for barrages had arisen at many other places.

Meanwhile the problem of defence against low-level bombing was only one aspect of a much wider question. A limitation of the Reorientation Plan and its predecessors—indeed, one inherent in all arrangements which fall short of an overwhelming air supremacy scarcely attainable during the early stages of any war—was that it aimed at inflicting casualties on the attacker and forcing him to fly high in order to escape destruction, but did not interpose an impregnable wall between him and his objectives. Important assets like arsenals, stores and bridges, unless they lay within the locally defended zones already contemplated, or were separately defended, would still be open to attack by the inevitable proportion of raiders which penetrated the aircraft fighting zone. To furnish all such places with local defences in the shape of heavy and light anti-aircraft guns, balloons and searchlights was quite out of the question, since it would disperse the available resources far too widely, thus leading to universal weakness rather than universal strength. The problem of striking a balance between undue dispersal and undue concentration was, however, clearly one which called for closer study than had been possible while war was only a remote hypothesis.

After the Reorientation Committee had themselves drawn attention to this weakness, the matter was studied by the Home Defence

* At the time of the Reorientation Committee’s report the establishment of an antiaircraft battery comprised eight 3-inch guns and twelve Lewis guns; that of a searchlight company, twenty-four lights and twenty-four Lewis guns. Stage I of the Reorientation Scheme would thus give 780 Lewis guns, apart from those at ports; the full scheme about four times that number.

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Committee.57 The inescapable conclusion was that nothing would suffice but a detailed reconnaissance of objectives whose claims to local defence deserved consideration. Clearly the first step was to draw up a list of such places, which included many industrial plants in private hands. Analogous duties with respect to places needing protection against sabotage were already performed by the Home Defence Committee. To their list of such ‘vulnerable points’ they now added a list of ‘vital points’ requiring protection from the air. It included such diverse objectives as factories, commercial oil installations, telegraph, telephone, wireless telegraph and cable systems, lighting and power plants, docks, mills, bridges and places where large quantities of food or other materials were stored, or would be stored in time of war.

In the summer of 1936 two inspecting officers (Brigadier E. H. Kelly and Air Commodore I. M. Bonham-Carter, later joined by Air Commodore A. J. G. Bird) began a lengthy tour by visiting twenty-five ‘vital points’ out of some two hundred already listed. They made a number of useful suggestions regarding the layout and structure of industrial buildings, the chances of confusing an attacker by means of camouflage and smoke-screens, and the most suitable organisation for passive air defence. They also recommended that light antiaircraft guns should be installed at three objectives and balloon barrages at two. Clearly these recommendations were only a foretaste of demands which would inevitably assume vast proportions as their tour progressed and the list of claimants lengthened. Moreover, large numbers of light anti-aircraft weapons would be needed at places outside the scope of the list, such as aerodromes and naval and army depots, and perhaps also aboard merchant vessels. Meanwhile a review of the anti-aircraft problem in the fight of the abolition of the outer artillery zone had raised the estimated requirement for heavy anti-aircraft guns and searchlights (including those at ports) to 608 and 2,547 respectively, as compared with the 544 and 2,334 envisaged in the Reorientation Plan of 1935.*58

In June 1936, the Committee of Imperial Defence approved the

* The following table shows the proposed distribution as between the air defence scheme proper and defended ports, and recapitulates the corresponding arrangements under earlier schemes which took ports into account:

Steel-Bartholomew Plan * Reorientation Plan† 1936 Review†
Guns Lights Guns Lights Guns Lights
Air Defence Scheme 192 504 456 2,160 ‡ 392 2,160
Defended Ports 72 168 88 174 216 § 387
264 672 544 2,334 608 2,547

* Includes Thames and Medway defences in defended ports.

† Includes Thames and Medway defences in air defence scheme.

‡ Includes 160 guns in mobile pool.

§ Includes 35 lights in reserve.

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review in principle; but the chances of giving effect to it seemed remote. Notwithstanding the limitations imposed in the previous year by the Government’s decision to approve only a truncated version of the Reorientation Plan, the War Office contemplated forming by the end of 1936 about three-quarters of the Territorial air defence units needed for the full scheme, equipping them gradually on a scale suitable for training. In the meantime the whole resources of the country amounted to about sixty usable anti-aircraft guns and a hundred and twenty searchlights.59 If the hopes of the General Staff were realised, the units would be equipped on a training scale by the spring of 1937, but would still be anything from sixty to eighty per cent, short of their war scale. Moreover, the gunners would have nothing but the 3-inch anti-aircraft gun, a standard weapon since the First World War but now due for replacement. The War Office wished to order enough new guns of larger calibre to meet the scale of defence laid down in the review, but could hold out no prospect of their being ready before the financial year 1938–1939. In the meantime something could be done by continuing to modify the older guns; but the number of modified guns available in 1937 would be comparatively small. In any case, their efficacy was doubtful, especially as the shell they fired was not of the most modern type. Unless a fresh solution was forthcoming, the air defence formations would thus be short of weapons for at least two years to come, and such guns as they did possess would be admittedly imperfect.

No answer had been found when, in the autumn of 1936, a confidential statement by the German Government confirmed the Air Staff’s view that the second stage of die German air expansion programme was drawing near completion.60 At the beginning of October the Luftwaffe could therefore be credited with the 114 squadrons predicted in 1934; but as their first-line strength was now put at nine machines instead of twelve, the total could be reckoned as roughly 1,100 instead of 1,368.* There seemed good reason to suppose that the further estimate of 1,500 aircraft in the spring of 1937 would also prove correct. Regarding the more distant future, the Air Staff had hitherto made no detailed forecast, although in the summer of 1934 they had predicted in general terms an ultimate intention to form ‘three or even four air divisions’, each presumably comparable with that foreshadowed in the first stage of the German programme.61 They now warned the Government that, in view of Germany’s more or less openly avowed intention of seeking parity with Russia, and also in view of recent signs that training and production were being hastened, a progressive increase ‘up to a figure of not less than 4,000 first-line aircraft’ must be expected.62

* See p. 27, footnote *.

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At the time of this announcement the first-line strength of the British metropolitan air force stood at 696 aircraft. It was due to rise to 1,736 aircraft on the completion of Scheme F in the spring of 1939. Plainly, parity had been lost and would not be regained without a much more drastic effort than the country seemed prepared for. With a view to putting a better complexion on the matter the Government considered a number of new programmes, but none held the field for long, or promised to make much difference to a situation which would depend in the long run on the ability of the aircraft industry and the Air Ministry to turn out machines and train crews to man them. In other words, the governing factor was the extent to which it seemed wise to divert to warlike ends the resources of a nation whose well-being was bound up with flourishing markets and sound trade.

In the meantime the Government had appointed Sir Thomas Inskip as Minister for Co-ordination of Defence. Pending a decision on the larger question, Sir Thomas invited the Reorientation Committee, which had remained in being under Dowding and was responsible for the recent review of the air defence scheme, to draw up a new scheme for the ‘ideal’ air defence of the United Kingdom, irrespective of conditions of supply.

As all past schemes had been conditioned by the knowledge that only meagre funds would be forthcoming, the new programme was inevitably far more ambitious than its predecessors. The Committee recommended in February 1937, that the defended zone should be extended northwards to a point beyond Newcastle and widened to cover the West Riding of Yorkshire and the Midlands.63 They also asked for more guns and searchlights at defended areas still outside the continuously defended zone, and for new defended areas covering the Clyde, the Forth and Bristol. The numbers of fighter squadrons, heavy anti-aircraft guns and searchlights contemplated, as compared with those previously envisaged, were:

Modified Reorientation Plan* New Plan
Fighter squadrons 30 45
Guns 608 1,264
Lights 2,547 4,700

In addition, up to three hundred twin-barrelled pom-poms seemed likely to be needed for defence against low-flying aircraft, besides upwards of four hundred balloons for the London barrage and an indeterminate number elsewhere. To cover the new defended areas additional Observer Groups would be necessary.

* The Reorientation Plan as modified by Scheme F and the review of 1936.

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Extension of the area covered by the Observer Corps was the cheapest and therefore the most readily accepted implication of the programme. The number of groups contemplated had already risen from sixteen to eighteen, new groups at Durham and Dunfermline having been sanctioned in 1936; and further additions to cover Bristol and the Clyde would present no major difficulty.64 But the rest of the proposals raised tremendous problems. Even if no fighter squadrons were needed on the Continent, the number provided by Scheme F would fall fifteen short of the new estimate; and the War Office could hold out no hope of finding the proposed number of heavy anti-aircraft guns and searchlights earlier than 1941. Light anti-aircraft guns and balloons would make yet further and still unpredictable demands on manpower and material resources. Indeed, so far-reaching were the implications of the ‘ideal’ scheme that there was some doubt whether it ought to be accepted even with the reservations which that term embraced. It could be argued that a strengthened bomber force might be the better bargain. Supporters of that thesis could point to the long-considered view of the Air Staff that the bomber arm was the country’s best protection and that purely defensive weapons should be kept to the essential minimum. But the real question was whether the ‘ideal’ scheme was not, as it was meant to be, that minimum.

In effect, the Committee of Imperial Defence gave their answer in the summer of 1937, when they approved the scheme in principle.65 Nine months later the German seizure of Austria underlined the threat to peace. Thereupon the Government made up their minds on the main issue by abandoning the rule that rearmament must not be allowed to interfere with normal trade. Soon afterwards they authorised the Air Ministry to order up to 12,000 aircraft for delivery by the spring of 1940, and, by accepting a new scheme of air expansion called Scheme L, committed themselves to an air force no longer designed to deter the potential enemy or match his strength, but to fight in face of odds.66