by Mark Felton
In December 1941 the Imperial Navy had available sixty-three operational submarines for immediate deployment on operations, a total that included forty-eight of the large I-boats. A further twenty-nine submarines were under construction in Japan, and were scheduled for completion in 1942–43. Their main opponent, the US Navy, had a total of 111 submarines in commission, with another seventy-three under construction. However, only fifty-one boats were assigned to the Asiatic and Pacific Fleets. The British no longer deployed a single submarine in the Pacific, or at any of its naval bases throughout south-east Asia, while the Netherlands had eleven boats assigned to her Asian colonies.8 Most Japanese submarines, certainly most of the powerful long-range I-boats were under the control of 6th Fleet. Vice-Admiral Mitsumi Shimizu would command this potent force consisting of the 1st, 2nd and 3rd Submarine Squadrons (each under a rear-admiral) from a forward base established soon after hostilities commenced at Kwajalein in the Marshall Islands. Shimizu’s flagship was the light cruiser Katori. Each submarine squadron was itself sub-divided into several divisions, each under the command of a sea-going captain, with individual submarines usually skippered by a lieutenant-commander. Combined Fleet Headquarters retained control over the 4th and 5th Submarine Squadrons, used to support to invasions of the Philippines and Malaya, with the 6th Squadron going to the 3rd Fleet (Blockade & Transport) also in support of the same amphibious operations. The 7th Squadron was under the operational control of 4th Fleet, and with its generally obsolescent vessels was tasked with protecting the Home Islands and the Mandated Islands under pre-war Japanese control in the Pacific. Finally, the Kure Naval District operated several second-line submarines that were considered unsuitable for open sea operations, and these vessels were used for crew training and homeland defence (see Appendix 1 for a complete breakdown of Japanese submarine organization at the beginning of the war.)
Fifty-two Japanese submarines displaced in excess of 3,000 tons, and at the war’s end they had even produced underwater aircraft carriers, the I-400-class, with a displacement exceeding 5,000 tons when submerged, and a length of over 400 feet. Forty-one of Japan’s Second World War submarines could carry aircraft, making the Imperial Navy the only fleet on earth capable of this innovation.9
Another innovation was in the field of torpedoes, and Japan was the world’s leader in their design. The famous Type 95 21-inch calibre torpedo, also known as the ‘Long Lance’, had the longest range of any torpedo then in existence, a mighty 12,000 metres at a speed of 45 knots. The 23-foot 5-inch weapon could deliver a warhead considerably more powerful than the best American torpedo, initially 893-pounds of TNT and hexani-trodiphenylamine, later increased to 1,080-pounds. What was truly revolutionary about the Long Lance was its propulsion system, another massive technological leap forward. The Type 95 burned oxygen in turn to ignite kerosene, instead of the more conventional compressed air and alcohol used by every other navy in the world. This meant that the Long Lance multiplied its range over Allied torpedoes, and the propulsion system drastically reduced any telltale wake of bubbles in the water that would allow enemy ships to take evasive action. A simple, yet highly reliable, contact exploder triggered the massive warhead, so the Japanese were not plagued as regularly by the kinds of torpedo failures suffered by German U-boats and American submarines in the earlier stages of the war.10
With advantages in submarine technology and torpedoes, innovations in submarine-mounted aircraft and massive patrol ranges, it is perhaps surprising that the Japanese were not more successful at sea during the course of the war. During the Pacific War’s early stages it was not the technology that was to fail Japan, but the strategic and tactical use of that technology against the Allies. Because of the entrenched belief in a large battle in the Western Pacific in reaction to the American’s ‘Plan Orange’, submarines were firmly tied to fleet cooperation, and not given over to commerce raiding as practiced by the larger German U-boat Service with such devastating results for Britain’s merchant marine. As we shall see, the operations discussed in this book marked Japan’s very quixotic attempts to interdict commerce and conduct fleet actions using submarines, and priority was always given to the fleet. Between 1939 and 1945 German U-boats sank 2,840 merchant ships, while Japanese submarines between the end of 1941 and 1945 sank 184. The difference in focus is clearly marked when one considers how potent a force the Japanese submarine fleet was, how devastating its weapons had the potential to be, and how well trained and above all determined were its men.
Even as the plans were being finalized for the series of attacks the Japanese desired to make on the colonial powers and the United States in December 1941, elements in the Imperial Navy still opposed opening a second war front before the army had successfully overcome resistance in China. Japan’s last senior dissenting voice to the proposed plan was Prince Konoye, the Prime Minister, and he was forced to resign in the face of intense pressure from the army on 18 October. His replacement sealed the fate of Japan and demonstrated to the world that Japan had become to all intents and purposes a military dictatorship. Serving army officer General Hideki Tojo succeeded to the post of Prime Pinister, and final plans for the decimation of the US Pacific Fleet were made on 1 November. On the 5 November 1941 Admiral Isoroku Yamamoto, commander of the Combined Fleet, issued the operational orders green lighting the air assault on Pearl Harbor. The purpose of the operation was to ‘damage U.S. forces sufficiently to keep them temporarily on the defensive and to prevent the American battle fleet from intervening with the Japanese southern advance’.11 The submarine part of the Combined Fleet attack on Pearl Harbor would consist of three elements, conducting three overall mission objectives. Firstly, the submarines would precede the main aircraft carrier fleet steaming towards Hawaii. As outlined in Admiral Yamamoto’s Combined Fleet Operations Order12 issued to the Japanese 6th Fleet (Submarines), the submarines were ordered to ‘Make reconnaissance of American Fleet in Hawaii and west coast areas and, by surprise attacks on shipping, destroy lines of communications’.13 The three vessels of the 2nd Submarine Division were allocated as a Patrol Unit to conduct the reconnaissance, with the I-19 acting as flagship, assisted by the I-21 and I-23. If the submarines sighted any enemy warships they were to track them, but were forbidden from launching any attacks until the air strike was under way. Following the air strikes, the submarines were to linger around the entrance to Pearl Harbor, and the area of ocean between Hawaii and the west coast and attack any American warships attempting to flee the carnage at Pearl Harbor. They were to also prevent the Americans from bringing reinforcements up to Hawaii from the mainland to reinforce the hopefully severely damaged Pacific Fleet. An attack was also to be made by midget submarines on Pearl Harbor slightly before the main air strike arrived aimed at sinking enemy warships found at anchor. In tactical command of all submarine forces involved in the Pearl Harbor operation was Rear-Admiral Tsutomu Sato aboard his flagship, the submarine I-9. His forces were derived from the 1st Submarine Squadron, and the Special Attack Force (midget submarines), subdivided into three separate units. The Carrier Strike Force would consist of two waves of torpedo and high-altitude naval bombers escorted by Zero fighters, flying from six aircraft carriers led by the Akagi, flagship of the Strike Force commander, Admiral Nagumo. The submarines of Vice-Admiral Mitsumi Shimizu’s 6th Fleet formed part of the Advance Expeditionary Force, but Admiral Sato retained tactical command at sea of the vessels involved in the operation. Shimizu’s force, which comprised all of 1st, 2nd and 3rd Submarine Squadrons, consisted of seventeen I-class submarines14 and five Type-A midgets. Operations Order No. 1 further elucidated upon the four functions the submarines of the Advance Expeditionary Force were to perform during the Pearl Harbor operation. Firstly, until X-day (7 December 1941) minus 3 days some of Shimizu’s submarines were to conduct covert reconnaissance of the Aleutian Islands, Fiji and Samoa, and were to report on any strong American naval forces discovered to be thereabouts. Secondly, one element was assigned to patrol the
route of the Striking Force, as it made its way across the Pacific. It was vital to protect the main force from enemy detection so the air strikes would come as a complete surprise. Thirdly, until X-day minus 5 the remaining submarines of the 6th Fleet were to surround Hawaii at extreme range while several boats approached the islands to reconnoitre. Fourthly, on X-day itself, submarines in the area were to ‘observe and attack the American fleet in the Hawaii area; make a surprise attack on the channel leading into Pearl Harbor [the job of the five midget submarines] and attempt to close it; if the enemy moves out to fight, he will be pursued and attacked.’15
In the meantime, to keep the Americans guessing as to Japan’s next move, diplomatic channels were kept open, culminating with Japanese Ambassador Nomura presenting Secretary of State Cordell Hull with a set of unacceptable demands in Washington DC on 26 November, the same day the massive Japanese carrier taskforce set sail from the Home Islands on a course for Hawaii.
The stage was thus set for one of history’s most memorable attacks, an attack largely remembered today not only for its treachery and surprise, but primarily for its innovative use of carrier aircraft against warships. One element of the Pearl Harbor attack that has often been overlooked was the role of Japan’s submarine service. The plan called for the Type-A midget submarines and their young crews to prove their worth and help Japan smash the power of the US fleet in a decisive aerial and submarine onslaught. Their success or failure to neutralize the American battle fleet on 7 December would have far reaching consequences for the entire Japanese strategic plan, and for the survival and prosperity of the empire Japan was about to carve out for itself in south-east Asia.
Notes
1. The final shots fired in anger on the American mainland between United States and British forces occurred at New Orleans, Louisiana in 1815, after the War of 1812 had been concluded. Due to the poor state of communications of the period news of a treaty agreement ending the war in 1814 was late reaching the respective generals.
2. Colin Smith, Singapore Burning: Heroism and Surrender in World War II, (London: Viking), 2005, p.59
3. Arthur Herman, To Rule the Waves: How the British Navy Shaped the Modern World, (London: Hodder & Stoughton), 2005, p.522
4. David Miller, U-Boats: History, Development and Equipment 1914–1945, (London: Conway Maritime Press), 2000, p. 14
5. Carl Boyd & Akira Yoshida, The Japanese Submarine Force and World War II, (Shrewsbury: Airlife Publishing Ltd.), 1996, p.14
6. Norman Polmar & Dorr B. Carpenter, Submarines of the Imperial Japanese Navy 1904–1945, (London: Conway Maritime Press), 1986, p.1
7. Lord Russell of Liverpool, The Knights of Bushido: A Short History of Japanese War Crimes, (London: Greenhill Books), 2002, p.31
8. Norman Polmar & Dorr B. Carpenter, op. cit.
9. Data derived from Bob Hackett and Sander Kingsepp’s website: http://www.combinedfleet.com/sensuikan.htm, from essay Japan’s Submarine Fleet
10. ibid, essay Japanese Torpedoes
11. Norman Polmar & Dorr B. Carpenter, op. cit., p.55
12. Combined Fleet Telegraphic Operations Order No. 021730
13. Japanese Monograph No. 97, Pearl Harbor Operations: General Outline of Orders and Plans, (Washington DC: Office of the Chief of Military History, Department of the Army), 1953, p.28
14. I-1, I-2, I-3, I-4, I-5, I-6, I-7, I-16, I-17, I-18, I-20, I-22, I-23, I-24, I-68, I-69, I-74
15. Report of the Joint Committee on the Investigation of the Pearl Harbor attack, Congress of the United States, (Washington DC: Government Printing Office), 1946, p.63
Chapter 2
Steel Coffins: 7 December 1941
In the first six to twelve months of a war with the United States and Great Britain I will run wild and win victory upon victory. But then, if the war continues after that, I have no expectation of success.
Admiral Isoroku Yamamoto before the Pearl Harbor
operation, 1941
On 28 November 1941 the Japanese First Special Attack Flotilla, consisting of the submarines I-16, I-18, I-20, I-22 and I-24, each carrying a single Type-A midget submarine clamped to the deck abaft the conning tower, began their journeys across the north Pacific to Hawaii. Aboard the I-22 was Captain Hanku Sasaki, commanding the flotilla, and he had issued orders that the submarines were to maintain a twenty-mile gap between one another as they journeyed across the ocean. Once out of Japanese territorial waters each submarine skipper informed the crew of their mission, and the purpose of the strange cargo they were hauling. Aboard the I-22, the skipper, Commander Kiyoi Ageta, declared to the assembled complement packed into the control room and the corridors leading away fore and aft: ‘Our ship is sailing for Hawaii now. Our objective is to discharge the special-type storage tube [a reference to the classified Type-A] to attack Pearl Harbor.’1 The leader of the midget submarines once the flotilla had launched from the mother ships was Lieutenant Naoji Iwasa who was also based aboard the I-22.
Captain Sasaki’s plan of action for the five midget submarines constituting his Special Attack Force was simple. The midgets were to penetrate Pearl Harbor undetected and stay concealed inside the harbour until the main air assault began. Several options were then open to the midget submarine skippers. Firstly, once the first Japanese aircraft appeared overhead, they could immediately begin attacks on American warships inside the harbour. Secondly, the midget submarine commanders could wait for the lull between the first and second Japanese aerial waves, and attack then, creating an offensive bridge between the first two aerial assaults. Thirdly, the midget submarines could continue to remain concealed throughout the duration of the carrier plane assaults, only to emerge from the depths with the coming of darkness, and as the Americans began cleaning up launch their attacks by travelling anti-clockwise around Ford Island. Regardless of which plan the submarine skippers activated, their aim was to expend their torpedoes and then depart Pearl Harbor and make for the rendezvous point with the mother submarines at Lanai Island and recovery. Of course, these plans hinged on any of the five Type-As actually penetrating the entrance to Pearl Harbor undetected.
The weapons, which the First Flotilla was to launch against Pearl Harbor hours before the arrival of the main aerial attack force, were intriguing creations reflecting Japanese ingenuity and the advance of naval warfare. The vessels were not small, each Type-A midget submarine measuring 78.5 feet in length and weighing forty-six tons. A two-man crew consisted of a junior officer who commanded the boat and an enlisted man who acted primarily as helmsman. The Type-A could managed 19 knots submerged, and had a potential maximum range of 100 miles if running on the surface at a conservative 2 knots. The midget would approach its target surfaced until diving for the final attack run. The role of the junior officer midget commander was to give helm orders and operate the submarine’s periscope. The commander decided the submarine’s course, speed and depth, and, of course, targets, and transmitted these orders to the petty officer helmsman. The petty officer was charged primarily with control of the helm, and he was required to keep his hands on the wheel for the duration of the mission as the midget was extremely sensitive and the helmsman could easily lose control of the vessel. The petty officer was also required to dive and surface the boat by pulling and turning an assortment of valves that operated the midget’s ballast tanks. Finally, when given the order by the commander, he was charged with firing the two 17 feet long 18-inch torpedoes loaded in the midgets two ‘under and over’ tubes in the bow. Each torpedo was packed with 300 pounds of TNT. The single greatest challenge faced by the midget crews, apart from heat exhaustion and being unable to stand up inside the vessel for hours on end, was maintaining the submarine’s balance, the Type-A being renowned for its instability at sea.2
The ‘mother’ submarines that would transport the midgets to the waters around Hawaii were all of the Type-C1-class. Five of these vessels were completed in 1940 and 1941 respectively,3 and they were dedicated midget submarine transports. As well
as the Pearl Harbor operation, the Type-C1 submarines I-16 and I-20 launched their midgets outside of the Royal Navy’s base at Diego Suarez in Madagascar on the night of 30 May 1942. Although neither the crews or the midget submarines themselves returned to the ‘mother’ ships they did manage to damage the old British battleship HMS Ramillies, and to sink the tanker British Loyalty inside the anchorage. The very next night, 31 May, thousands of miles to the east, the I-22 and I-24 (along with other Japanese submarines) launched their midgets in an attempt to penetrate Sydney harbour in Australia (related in Chapter 5).
In November 1942 the I-16, I-20 and I-24 all launched midgets off Guadalcanal, but the damage inflicted to a single American transport was a heavy price to pay for the loss of all of the Type-A midgets that participated in the operation.
When fully loaded the 358.5 feet long Type-C1 submarine weighed in at 3,561 tons, and was powered by twin diesel engines generating 12,400 horsepower. This meant that the submarine could reach 23.5 knots on the surface, and an equally impressive 8 knots when running submerged on 2,000 horsepower electric motors. At a fuel-conserving 16 knots a surfaced Type C1 could sail 14,000 nautical miles without refuelling. However, the boats’ trim characteristics were shot to pieces by each having a forty-six ton midget submarine armed with two torpedoes secured to their decks. The submarines travelled submerged by day to avoid aerial detection, coming to the surface at night to charge their batteries. Heavy winter seas constantly washed over the submarines’ decks as the maintenance crews charged with taking care of the midgets clambered and skidded about. The crewmen had to tie themselves to the submarines with lifelines, and many were washed overboard by the waves, only to climb back onto the decks bruised, exhausted and coughing up seawater. Onboard the I-24 one of the midget’s torpedoes was damaged when the mother ship submerged, and it took the crew a full night in foul weather to fit a new torpedo, manhandling the steel fish up from inside the cluttered and cramped interior of the I-24 and into the midget.