Planning for an Unpredictable War: British Intelligence Assessments and the War Against Japan, 1937–45

Abstract

Britain's ability to develop a coordinated strategy during the Pacific War was hindered by two key factors. The first of these was the persistent difficulties involved in predicting Japanese war plans, which meant that British strategy had to develop on an ad hoc basis. Second, British strengths in the Far Eastern theaters were consistently limited by more pressing commitments arising from the war against Germany, thereby requiring Britain to cope with its Japanese adversary by employing its scarce resources in an economical manner. The intelligence pointing to the unpredictability of Japan's strategy and the disparity between the opposing forces in the Far East, in turn, played a crucial role in shaping the evolution of a strategy that was within Britain's capacity to implement.

Notes

Douglas Ford recently completed his PhD in International History at the LSE, and currently holds a lectureship at the International Politics Department at the University of Wales, Aberystwyth. His fields of specialization are Allied and Japanese military policy during the inter-war period and the Pacific War, with a focus on the role of intelligence.

See F.H. Hinsley et al., British Intelligence in the Second World War, Volumes I–IV, in series History of the Second World War (London: HMSO 1979–90).

A. Best, British Intelligence and the Japanese Challenge in Asia, 1914–1941 (London: Macmillan 2002) chs 7–9; R.J. Aldrich, Intelligence and the War Against Japan: Britain, America and the Politics of Secret Service (Cambridge: Cambridge UP 2000) chs 2–5.

Liddell Hart Center for Military Archives, King's College London (hereafter LHCMA) Pownall Diaries – 25 Feb. 1942.

This analysis is based on deductions arrived at through archival research as well as information obtained from published sources. Information on the various bodies responsible for intelligence collection and analysis has been compiled from Aldrich (note 2); Best (note 2); P. Elphick, Far Eastern File: the Intelligence War in the Far East, 1930–45 (London: Hodder & Stoughton 1997); Hinsley (note 1); and ‘British Intelligence in the Second World War’, in C. Andrew and J. Noakes (eds.), Intelligence and International Relations, 1900–1945 (Exeter UP 1987) pp.209–18; S.W. Kirby, The War Against Japan, Volume I, in series History of the Second World War (London: HMSO 1957–70); P. Lowe, ‘Great Britain's Assessment of Japan Before the Outbreak of the Pacific War’, in E. May (ed.), Knowing One's Enemies: Intelligence Assessment before the Two World Wars (Princeton UP 1984) pp.456–75; E. Thomas, ‘The Evolution of the JIC System up to and during World War II’, in Andrew and Noakes (above) pp.219–34.

See M. Barnhart, Japan Prepares for Total War: the Search for Economic Security, 1919–41 (Ithaca: Cornell UP 1987); R.J.C. Butow, Tojo and the Coming of War (Stanford: Stanford UP 1961); N. Ike (ed.), Japan's Decision for War: Records of the 1941 Policy Conferences (Stanford UP 1967); A. Iriye, The Origins of the Second World War in Asia and the Pacific (London: Longman 1987); J.W. Morley (ed.), The Fateful Choice: Japan's advance into Southeast Asia, 1939–41 and The Final Confrontation: Japan's negotiations with the United States, 1941, both selected translations from series taiheiyo senso e no michi: kaisen gaiko shi, English translation – Japan's Road to the Pacific War (NY: Columbia UP 1983–94); I.H. Nish, Japanese Foreign Policy, 1869–1942 (London: Routledge & Kegan Paul 1977).

Ike (note 5) p.50.

Public Record Office, Kew Gardens, Surrey, England (hereafter PRO) CAB 80/3 COS (39) 52 Sino-Japanese Hostilities: Memorandum by COS – 28 Sept. 1939.

L. Allen, Singapore, 1941–1942 (Newark, DE: Delaware UP 1977) p.44; O.C. Chung, Operation MATADOR: Britain's War Plans against the Japanese, 1918–41 (Singapore: Times UP 1997) p.71.

PRO CAB 80/15 COS (40) 592 Situation in the Far East in the Event of Japanese Intervention: Report by COS – 15 Aug. 1940.

PRO ADM 223/15 Admiralty Weekly Intelligence Summary (hereafter ADMWIS) Nos. 72 and 73 – 25 July and 1 Aug. 1941.

R.J. Aldrich, The Key to the South: Britain, the US and Thailand during the approach of the Pacific War, 1929–42 (Oxford: Oxford UP 1993) chs 5–8.

PRO CAB 81/99 JIC (41) 11 Sea, Land and Air Forces Which Japan Might Make Available for Attack on Malaya: Report by JIC – 6 Jan. 1941; CAB 81/105 JIC (41) 449 Possible Japanese Action: Report by JIC – 28 Nov. 1941.

Imperial War Museum, London (hereafter IWM) Percival Papers P 49 Some Personal Observations of the Malaya Campaign, 1940–42: prepared by B.H. Ashmore – 27 July 1942.

PRO CAB 96/7 FEC (E) (41) 27 Japanese Pig and Iron Ore Supplies: Memorandum by Ministry of Economic Warfare – 27 May 1941; FO 837/539 Japanese Aviation Spirit Supplies: Extract from Air Ministry Weekly Intelligence Summary (hereafter AMWIS) – 5 March 1941.

PRO CAB 80/29 COS (41) 474 (Annex) Report by JPS – 3 Aug. 1941.

PRO WO 208/877 BJ.091114: Tokyo to Berlin – 31 July 1941 (decrypted on 6 Aug.).

PRO WO 208/870 War Office Appreciation of Situation in Far East – 6 April 1941; CAB 69/2 Cabinet Defense Committee (Operations) 30th meeting – 15 May 1941; WO 193/864 MO1 Memorandum – 19 Aug. 1941.

PRO CAB 69/2 Cabinet Defense Committee (Operations) 65th meeting – 17 Oct. 1941.

Quoted from PRO ADM 205/9 Personal Letter from Pound (First Sea Lord) to Little (BAD Washington) – 6 Dec. 1941.

PRO HW 1/504 BJ.103370: Tokyo to Berlin – 17 April 1942 (decrypted on 20 April); HW 1/546 BJ.104008: Tokyo to Berlin – 4 May 1942 (decrypted on 7 May). For a concise account of the British government's perceptions regarding this problem, see Aldrich (note 2) pp.157–64.

Elphick (note 4) pp.348–50.

Ibid. pp.350, 3535; Aldrich (note 2) p.237.

E. Drea, In the Service of the Emperor: Essays on the Imperial Japanese Army (Lincoln: Nebraska UP 1998) pp.32–7.

P.S. Dull, A Battle History of the Imperial Japanese Navy, 1941–45 (Annapolis, MD: Naval Institute Press 1978) pp.98–9; H.P. Willmott, Empires in the Balance: Japanese and Allied Pacific Strategies to April 1942 (Annapolis, MD: Naval Institute Press 1982) pp.439–40.

PRO CAB 81/106 JIC (42) 75 (Final) Enemy Intentions: Report by JIC – 14 March 1942.

PRO FO 371/31810 F 3615/4/23 Cipher No.11045/PR: Wavell to War Office – 6 May 1942; Cipher No.86999: War Office to Wavell – 7 May 1942.

J.R.M. Butler, Grand Strategy, Volume III, Part 2 in series History of the Second World War (London: HMSO 1956–76) pp.484–5; H. Probert, The Forgotten Air Force: the Royal Air Force in the war against Japan, 1941–1945 (London: Brassey's 1996) pp.115–16

PRO WO 106/3759 Cipher No.8435/C: Wavell to COS – 8 April 1942; WO 106/3493 COS Appreciation of Situation in Indian Ocean Theater – 23 April 1942 (cited in Kirby (note 4) Volume II, p.128).

PRO CAB 79/20 COS (42) 102nd Meeting – 1 April 1942; PREM 3/163/8 Naval Cypher No.1204Z/3: Personal Telegram from Pound to Admiral King – 3 April 1942; ADM 205/13 Churchill's Personal Minutes T.547/2 and T.570/2 for Roosevelt – 7 and 15 April 1942, respectively

Kirby (note 4) Volume II, pp.127–30; Butler (note 27) pp.487–9.

S.W. Roskill, The War at Sea, Volume II, in series History of the Second World War (London: HMSO 1954–61) p.29; A. Marder, Old Friends, New Enemies: the Royal Navy and the Imperial Japanese Navy, 1936–45, Volume II, The Pacific War, 1942–45 (Oxford: Oxford UP 1990) pp.137–42.

M. Howard, Grand Strategy, Volume IV, in series History of the Second World War (London: HMSO 1956–76) pp.79–80.

PRO CAB 80/67 COS (43) 33 (O) Enclosure - ‘SYMBOL’: Combined Chiefs of Staff (CCS) 55th and 59th Meetings – 14 and 17 Jan. 1943; Howard (note 32) pp.245–52.

PRO CAB 84/40 JP (FE) (42) 3 Appreciation of the War Against Japan (Stage I): Summary of Conclusions by FPS – 14 March 1942.

PRO CAB 79/56 COS (42) 72nd Meeting (O) – 11 July 1942.

oward (note 32) pp.250–52.

PRO CAB 84/50 JP (42) 949 Strategy in the Southwest Pacific: Report by JPS – 12 Nov. 1942.

H.P. Willmott, The War With Japan: the Period of Balance, May 1942–October 1943 (Wilmington, DE: Scholarly Resources 2002) pp.90–9.

PRO CAB 81/110 JIC (42) 337 (O) Annex: Air Ministry to Britman (Washington) – ?? 1 Sept. 1942; WO 106/3759 Cipher No.24583/C: Armindia to Air Ministry – 5 Oct. 1942.

PRO CAB 80/65 COS (42) 345 (O) (Final) American-British Strategy: Report by COS – 30 Oct. 1942

PRO WO 106/2692 Operations in Burma 1942/43: Report by MO1 (Records); CAB 79/57 COS (42) 132nd Meeting (O) – 30 Sept. 1942.

LHCMA ALANBROOKE 6/2/6 f.8B Operation FANTASTICAL: Most Secret Memorandum by Wavell for Alanbrooke (CIGS) – 17 Sept. 1942.

W.J. Slim, Defeat into Victory (London: Cassell 1956) p.150.

PRO CAB 106/59 Operations in the Eastern Theater based on India from March 1942 to Dec. 1942: dispatch by Wavell for War Office – 18 Sept. 1946.

See M. Barnhart, ‘Japanese Intelligence Before the Second World War: best case analysis’, in May (ed.) (note 4) pp.440–55; A.D. Coox, ‘Flawed Perception and its Effect Upon Operational Thinking: the case of the Japanese Army, 1937–41’, in M. Handel (ed.), Intelligence and Military Operations (London: Frank Cass 1990) pp.242–53.

S. Hayashi, in collaboration with A.D. Coox, Kogun: the Japanese Army in the Pacific War (Quantico, VA: Marine Corps Association 1959) pp.72–3.

PRO ADM 223/297 NID Vol.42 Far East and Pacific, III, Special: HMS Anderson and special intelligence in the Far East; Aldrich, Intelligence and the War Against Japan (note 2) pp.239–47.

Marder (note 31) p.460.

T. Koyanagi, ‘The Battle of Leyte Gulf’, in D.C. Evans (ed.), The Japanese Navy in World War II, 2nd edn. (Annapolis, MD: Naval Institute Press 1986) pp.356–61.

Drea (note 23) pp.131–2.

PRO ADM 223/163 Special contribution: ‘Tactical foresight’ (US Pacific Fleet Confidential Bulletin, dated May 1944), in ADMWIS No.233 – 25 Aug. 1944.

Drea (note 23) p.131.

PRO CAB 79/60 COS (43) 68th Meeting (O) – 7 April 1943 – Enclosure: JIC (43) 144 (O) (Final) Combined Intelligence in the SWPA and India: Report by JIC – 5 April, 1943, Annex A – Telegram No.43911/COS: Wavell to COS – 26 March 1943, Annex B – Reply to above.

Churchill College Cambridge Archives Centre (hereafter CCC) SMVL 8/3 Somerville to Mountbatten – 24 April 1944.

PRO AIR 40/2694 Strategic employment of the JAAF and JNAF – summer 1944: by AI3d – 5 Oct. 1944, Comments on above by Headquarters ACSEA – 6 Nov. 1944.

PRO WO 208/147 Intelligence Notes from Burma: published by GSI (x), GHQ India – Oct. 1945 (hereafter Intelligence Notes from Burma), Part I – Notes by Headquarters 14th Army on Intelligence During the Burma Campaign, May 1944 – May 1945; R. Lewin, The Other ULTRA: Codes, Cyphers and the Defeat of Japan (London: Hutchinson 1982) pp.196–8; A. Stripp, Codebreaker in the Far East: How Britain Cracked Japan's Top Secret Military Codes (Oxford, OUP 1989) pp.80–89; F.W. Winterbotham, The ULTRA Secret (London: Weidenfeld 1974) p.204. This author must admit that much of the information on this issue has been obtained from Aldrich (note 2) pp.252–4.

Aldrich (note 2) p.253.

See Hayashi (note 46) p.95.

Intelligence Notes from Burma, Part I.

Ibid., Part II – Intelligence in a Corps (Based on experiences gained by the 4th Corps on Assam–Burma frontier during May 1942 to July 1944).

L. Allen, Burma: the Longest War, 1941–45 (London: Dent 1984) pp.188–9, 228; IWM Scoones Papers, Appreciation of the situation in the event of a major enemy attack materializing in the next two months: by Scoones – 29 Feb. 1944.

PRO WO 203/5037A DMI/442 Japanese reinforcement of Burma: Summary of Military Intelligence views on information received and sources available – 11 Sept. 1943.

PRO CAB 81/114 JIC (43) 196 (Final) Japanese Strengths in the Pacific: Report by JIC – 30 April 1943.

PRO CAB 84/61 JP (44) 55 (Final) Appendix – Security of Imperial Communications in the Indian Ocean: Memorandum by COS – 27 Feb. 1944; CAB 81/121 JIC (44) 75 (O) (Final) Japanese Naval Moves: Report by JIC – 24 Feb. 1944.

PRO CAB 79/89 COS (44) 62nd Meeting (Confidential Annex) – 25 Feb. 1944; CAB 120/518 Serial No.78/4: Personal Minute by Churchill to COS – 7 March 1944; CAB 120/611 SEACOS No.115: Mountbatten to Air Ministry, enclosing signal from Somerville – 17 March 1944.

Note: In reality, there was no such organization as the Japanese Air Force per se. The navy and army operated their own separate air arms. However, for the purpose of the article, the acronym JAF will be used to describe the Japanese air services in general.

PRO CAB 81/115 JIC (43) 282 (Final) Axis Strength, 1943–44: Report by JIC – 1 Aug. 1943; AIR 22/78 AMWIS Nos 187, 200, 204 – 3 April, 3 and 31 July 1943; AIR 23/7720 Air Command Southeast Asia Weekly Intelligence Summary (hereafter ACSEAWIS) No.14 – 20 Feb. 1944; AIR 23/7722 ACSEAWIS No.33 – 2 July 1944.

PRO CAB 84/53 JP (43) 89 (O) Operation ANAKIM – Cover Plan: Report by Controlling Officer on Field Marshal Wavell's proposals – 25 Feb. 1943.

PRO CAB 81/113 JIC (43) 73 (Final) Japanese Intentions: Report by JIC – 24 Feb. 1943; CAB 81/122 JIC (44) 186 (O) (Final) Japanese Intentions: Report by JIC – 6 May 1944.

PRO WO 208/2263 War Office Weekly Intelligence Summary No.181: Annex 7 – 3 Feb. 1943, No.189 – 31 March 1943, No.190 – 7 April 1943, No.191 – 14 April 1943, No.192 – ‘An unsuccessful Japanese reinforcement operation’ – 21 April 1943, No.199 – ‘Japanese supply problems in the field’ (From G-2 Information Bulletin No.10, Headquarters US Army Forces in South Pacific Area) – 9 June 1943.

PRO WO 203/303 Appreciation on Capture of Akyab: by Rear Headquarters SEAC – (Undated ?? late June/early July 1944).

PRO AIR 23/3020 SAC (44) 63 Arakan Operations, 1944: Note by C-in-C Army Group Southeast Asia (Headquarters SACSEA, New Delhi) – 30 Jan. 1944.

PRO CAB 80/73 COS (43) 471 (O) Enclosure – JS (QUADRANT) 6 Operations in Sumatra: Report by JIC – 8 Aug. 1943; CAB 81/117 JIC (43) 369 (O) (Revised Final) Operations Against Northern Sumatra: Report by JIC – 27 Sept. 1943; JIC (43) 372 (O) (Final) Operations for the direct capture of Singapore: Report by JIC – 27 Sept. 1943.

PRO CAB 81/116 JIC (43) 337 (O) (Final) Sumatra-Malaya: Report by JIC – 17 Aug. 1943.

LHCMA ISMAY 4/30/8a Somerville to Ismay (Cabinet Secretary) – 22 Feb. 1944.

John Rylands Library, University of Manchester (hereafter JRL) AUCHINLECK 1034 Note on size and composition of Indian Army, c.31 Aug. 1943.

Southampton University Library Mountbatten Papers C50/10 dated 27 Nov. 1943, C50/11 SC4/10/C dated 3 Jan. 1944, both from Mountbatten to Alanbrooke; PRO CAB 106/75 Report to CCS by SACSEA 1943–46 – dated 30 July 1947.

JRL AUCHINLECK 1351 File XLVIII: Despatches, etc., on the Indo-Burma front between 21 June and 15 Nov. 1943 by Sir Claude J.E. Auchinleck for Secretary of State for War – 1947; Slim (note 43) pp.169–77.

IWM Scoones Papers, Appreciation of the situation in the event of a major enemy attack materializing in the next two months: by Scoones – 29 Feb. 1944; Narrative of 4th Corps operations between March–July 1944 by General Sir G. Scoones – Vol. III, Chapter XX, The Battles of Imphal and Kohima: The Japanese Advance Halted.

IWM Scoones Papers, Draft Narrative on the reconquest of Burma; Slim (note 43) pp.290–92.

Kirby (note 4) Volume II, pp.362–3, 368–70; Howard (note 32) pp.399–401, 437–8.

PRO CAB 79/65 COS (43) 229th Meeting (O) Enclosure – Operations in Southeast Asia: Aide-Memoir by JPS – 28 Sept. 1943; COS (43) 231st Meeting (O) – 30 Sept. 1943; COS (43) 240th Meeting (O) Enclosure – Operations in Southeast Asia in 1944: Report by JPS – 6 Oct. 1943

H.P. Willmott, Grave of a Dozen Schemes: British Naval Planning and the War against Japan, 1943–45 (London: Airlife 1996).

A. Bryant, Triumph in the West (London: Collins 1959) p.44; Marder (note 31) pp.276, 301.

Ibid., pp.295–6.

CCC CHAR 20/104/2 Churchill's Personal Minute D (Q) 13/3 for COS, enclosing his reply to JS (Q) 12 – Operation ‘CULVERIN JUNIOR’: Report by JPS (Annex I) – 17 Aug. 1943.

Marder (note 31) p.301.

See D. Fraser, Alanbrooke (NY: Atheneum 1982) pp.412–13.

Quoted from Marder (note 31) p.556.

PRO CAB 79/77 COS (44) 236th Meeting (O) – 14 July 1944.

PRO WO 208/146 The Japanese Campaign in the Arakan, Dec. 1943–Feb. 1944: issued by GHQ India Military Intelligence Directorate; Probert (note 27) p.172.

Royal Air Force Museum, Hendon, London Peirse Papers AC71/13/79 SCM/322/44: Personal Memorandum for Commanders-in-Chief on Mountbatten's visit to the Burma Fronts – 6 July 1944; Slim (note 43) pp.347–8, 351–2.

LHCMA GRACEY 2/12 Appreciation of Situation by Stopford (GOC 33rd Corps) – 30 June 1944; Kirby (note 4) Volume III, pp.361–2.

LHCMA GRACEY 2/25 Joint Appreciation of situation to cover offensive action in Burma during autumn 1944 by Commander of 33rd Corps and AOC 221st Air Group RAF – 18 Sept. 1944; PRO CAB 81/127 JIC (45) 13 (O) (Final) Japanese Strategy in Burma: Report by JIC – 15 Jan. 1945.

PRO PREM 3/149/8 SAC 7296: Personal for Churchill from Mountbatten – 29 Sept. 1944; WO 193/907 SAC 12471: Mountbatten to COS – 22 Dec. 1944.

Slim (note 43) pp.481, 487; Allen (note 61) pp.459–60; Kirby (note 4) Volume IV, pp.327–8.

Bryant (note 84) pp.248–50.

PRO CAB 80/86 COS (44) 703 (O) (Final) Operations in Burma: Aide-Memoire by COS – 7 Aug. 1944; CAB 79/79 COS (44) 264th Meeting (O) – 8 Aug. 1944.

Ibid.; D. Fraser, And We Shall Shock Them: the British Army in the Second World War (London: Hodder 1983) p.363; Kirby, Vol. IV, p.7; J. Ehrman, Grand Strategy, Volume V, in series History of the Second World War (London: HMSO 1957–70) pp.495–6.

Kirby (note 4) Volume V, pp.75–86.

Ibid. pp.66–70.

Ibid. pp.87–88; PRO CAB 120/704 SEACOS 431: Mountbatten to COS – 10 July 1945; CAB 79/36 COS (45) 192nd Meeting – 7 Aug. 1945; CAB 69/7 Defense Committee (45) (Operations) 2nd Meeting – 8 Aug. 1945.

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Notes on contributors

Douglas Ford

Douglas Ford recently completed his PhD in International History at the LSE, and currently holds a lectureship at the International Politics Department at the University of Wales, Aberystwyth. His fields of specialization are Allied and Japanese military policy during the inter-war period and the Pacific War, with a focus on the role of intelligence.