2. Prior to 1941 Japanese naval war planning had not envisaged offensive operations as far east as Hawaii. Naval strategy against the United States called for the capture of the Philippines and Guam, depriving the American fleet of its operating bases in the Western Pacific, and then awaiting attack in Japan's sphere of naval superiority. In 1941, however, plans had to be revised to meet the possibility of war against both the United States and Britain. In September 1941 Admiral Yamamoto, Commander-in-Chief of the Combined Fleet, began advocating a new plan calling for an attack on Pearl Harbor, designed to cripple the American fleet at the start of hostilities. This, he argued, was essential to give Japan control of the Western Pacific for the period necessary to carry out operations in the Southern Area. The plan, however, met strong opposition by the Operations Bureau, Imperial General Headquarters, Navy Section on the ground that it was too risky and would divert too much fleet strength from the Southern Operations, compromising their success. After Admiral Yamamoto had threatened to resign his command unless the plan were adopted, it was finally approved by Admiral Osami Nagano, Chief, Navy General Staff, Imperial General Headquarters, Navy Section, on 20 October. (Statement by Rear Adm. Sadatoshi Tomioka, Chief, First Bureau (Operations), Imperial General Headquarters, Navy Section)
3. (1) Nampogun Sakusen Kiroku (Southern Army Operations Record) 1st Demobilization Bureau, Jul 46, pp. 8-9. (2) Statements by Lt. Gen, Shinichi Tanaka, Chief, First Bureau (Operations), and Col. Takushiro Hattori, Chief, Operations Section, both of Imperial General Headquarters, Army Section.
5. Fastest troop transports were assigned to the Malayan invasion, leaving only the slower ships for the Philippines operation. (Statement by Col. Ichiji Sugita, Staff Officer (Intelligence), Imperial General Headquarters, Army Section)
6. "The method of attack for the Philippines differed from that for the Malaya area. In the former operation, an air offensive to annihilate enemy air strength was to be carried out first, after which advance troops would capture enemy air bases and finally the main forces would be landed." Southern Army Operations Record, op. cit., p. 25. Cf. Chapter VI.
7. Hasty construction of an airfield on Phuquoc Island, off the southwest coast of Indo-China, during the first part of November 1941, helped to extend slightly the range of Indo-China based fighter planes. From this field fighters were able to cover the landings of the main Malaya invasion forces at Singora and Pattani, in southern Thailand, but effective cover for the diversionary landing at Kota Bharu, farther south, remained difficult. ATIS Enemy Publications No. 278, Malaya Campaign 1941-1942. 11 Jan 45, p. 10.
11. Regular Army strength was estimated at about 232,000, the remainder consisting of volunteer and native troops. Plane strength was estimated by area as follows: Malaya, 200 plus; Burma, 50; Hongkong 10; Philippines, 160 plus; Netherlands East Indies, 300. Daihonyei Rikugun Tosui Kiroku (Imperial General Headquarters Army High Command Record) 1st Demobilization Bureau, Nov 46, pp. 37-41.
12. The United States was believed to have eight battleships and three aircraft carriers at Hawaii, while British strength was estimated at two battleships in the Malaya area and two to six battleships and two or three aircraft carriers in the Indian Ocean area (including East and Southeast Africa). United States Strategic Bombing Survey, Japan's Struggle to End the War. Appendix A, p. 18.
17. The Imperial Guards Division was temporarily transferred to the Fifteenth Army for initial operations (pacification of Thailand) but was then restored to the Twenty-fifth Army for participation in the Malaya campaign.
18. The Japanese Navy employed this term to cover combat forces for employment in operations outside Japanese home waters, as distinguished from the "inner combat force" which operated only in home waters.
22. The original text of Combined Fleet Top Secret Operations Order No. 1 was recovered from the Japanese cruiser Nachi, sunk in Manila Bay, in April 1945. Translated in full in ATIS Limited Distribution Translation No. 39 (Part VIII), 4 Jun 45, pp. 2-54. The contents of Combined Fleet Top Secret Operations Order No. 1 had been worked out during October, but it was not drawn up in final form until Admiral Yamamoto and his staff were summoned to Tokyo early in November in anticipation of the Imperial conference decision. The order numbered approximately 120 pages and was reproduced in 700 copies.
24. In case of a serious enemy attack before X-Day, the Combined Fleet Top Secret Operations Order No. 1 stipulated that "forces attacked will counterattack immediately." It further directed that military force might be used after "Second Preparations for War" had been ordered, (1) " if American, British or Dutch ships or planes approach the vicinity of our territorial waters and their action is deemed to constitute a danger"; (2) "if our forces operating outside the vicinity of our territorial waters encounter positive actions by American, British or Dutch forces such as endanger our forces." ATIS Limited Distribution Translation No. 39 (Part VIII), op. cit., p. 5.
25. As a special precaution to guard the secrecy of the Pearl Harbor attack plan, the bracketed portions were left blank in the printed text of the order and were communicated verbally only to a restricted number of high Navy General Staff officers and staff officers of Combined Fleet, First Air Fleet and Sixth Fleet Headquarters. Statement by Rear Adm. Tomioka, previously cited.
26. Separate Table 1 of the Combined Fleet Top Secret Operations Order No. 1 specified that the South Seas Force would "invade Wake and Guam" and would also "invade Rabaul if the situation warrants" during the first period of hostilities. ATIS Limited Distribution Translation No. 39 (Part VIII), op. cit., p. 45.
27. Part VIII of the Combined Fleet Top Secret Operations Order No. 1 outlined Second Phase Operations to begin after the capture of the Netherlands East Indies, specifying the following areas "to be occupied or destroyed as speedily as operational conditions permit": (1) Eastern New Guinea, New Britain, Fiji and Samoa; (2) Aleutians and Midway; (3) Andaman Islands; (4) Strategic points in the Australian area. Ibid., pp. 6, 9.
30. This directive was implemented by a Combined Fleet Operations Order dated 22 November, which stated: "In the event an agreement is reached in the negotiations with the United States, the Task Force will immediately return to Japan." Ibid.
36. The agreement fixed the areas to be occupied as the Philippines, Guam, Hongkong, British Malaya, Burma, the Bismarcks, Java, Sumatra, Borneo, the Celebes, and Timor. Initial attack plans followed the lines of Combined Fleet Order No. 1, and Army and Navy strength was allotted as already outlined on pp. 60-2. Nampo Sakusen Chuo Kyotei (Army-Navy Central Agreement, Southern Operations) Japanese Government Demobilization Bureaus, Nov 45. pp. 4-11.
37. Four agreements were concluded, as follows : (1) 2d Fleet-14th Army; (2) 2d Fleet-16th Army; (3) 4th Fleet-South Seas Detachment; (4) 11th Air Fleet-5th Army Air Force. A fifth operational agreement covering the Malaya invasion was reached at Saigon in the middle of November between the 25th Army, the Southern Expeditionary Fleet and the 3d Air Group.
43. Had refueling at sea been impossible due to rough weather, it was planned that the destroyer screen would separate from the Task Force and return. The cruising range of other Task Force units, which normally could not have operated beyond 160 degrees West, was extended by loading extra drums of heavy oil on deck and in empty spaces below decks. ATIS Research Report No. 131, op. cit., p. 67.
45. (1) Ibid., pp. 58-9. (2) An Imperial General Headquarters Navy Information Bureau communique issued at 1300 18 December announced the results as: "Sunk5 battleships, 2 A or B-Class cruisers; heavily damaged3 battleships, 2 light cruisers, 2 destroyers; medium or light damage1 battleship, 4 B-Class cruisers. 450 enemy planes destroyed by bombing and strafing; 14 shot down." ATIS Research Report No. 132, The Pearl Harbor Operation, 1 Dec 45, p. 17.
46. These craft were carried aboard long-range "mother" submarines fitted with a mechanism for releasing them in the zone of operations. Mechanical improvements and training of the crews were completed barely in time to permit their employment in the Pearl Harbor operation.
49. One of the midget submarines which failed to penetrate into the harbor attacked small enemy craft on 8 December until it was finally disabled. One of its two crew members, Ensign Sakamaki, was taken prisoner and was the only survivor.
52. The Guam invasion force (South Seas Detachment) sailed from Haha-Jima, in the Bonins, on 4 December. Kaigum Nanyo Butai Sakusen no Gaiyo narabini Butai Shisetsu no Ippan Jokyo (Outline of South Seas Naval Force Operations and General Situation of Facilities) 2d Demobilization Bureau, Jul 49, p. 3.
54. Landings began at the following times: Kota Bharu 0215 (0015 Malay Time); Singora 0410 (0210 M.T.); Pattani 0430 (0230 M.T.) Marai Sakusen Kiroku Dai Nijugo Gun (Malay Operations Record: Twenty-fifth Army) 1st Demobilization Bureau, Sep 46, pp, 42-3.
56. This striking success bolstered Japanese morale and strongly influenced subsequent air operational methods. Two Japanese accounts of the engagement are published in ATIS Enemy Publications No. 6, The Hawaii-Malaya Naval Operations, 27 Mar 43, pp. 12-8.
58. Imperial General Headquarters on 22 January issued an order to the Commander-in-Chief, Southern Army, to launch operations jointly with the Navy for the occupation of important points in Burma. Imperial General Headquarters Army High Command Record, op. cit., p. 83.
62. Imperial General Headquarters Army Order to Commander-in-Chief, China Expeditionary Forces, 1 December 1941: "1. Commander-in-Chief, China Expeditionary Forces, in cooperation with the Navy, will capture Hongkong, using as the main body the 38th Division under the command of the Commanding General, Twentythird Army." 2. Operations will commence immediately after the landings in Malaya or upon confirmation of the air attack." Imperial General Headquarters Army High Command Record, op. cit., p. 75.