by Mark Felton
Nambu next spent several days hanging around the approaches to Sydney without sighting a single ship, which was unusual considering the density of merchant and warship traffic travelling in and out of the port. At 2 p.m. on 13 June Nambu finally sighted a small convoy of approximately six transport ships, escorted by a pair of destroyers, about thirty miles east of the Wollongong Lighthouse. Once again, the I-174 surfaced too far from the ships to allow an interception to be attempted and Nambu was forced to submerge again and wait. The next night, another Beaufort on anti-submarine duty pounced on the I-174, and the submarine narrowly avoided a hail of bombs. After staying submerged for over half an hour Nambu resurfaced only to discover that the Australian aircraft was still circling the area and he was attacked again and forced once more beneath the waves.
On 16 June, when the I-174 was south-east of Coffs Harbour, Nambu finally discovered a convoy that he was in a position to attack. Five corvettes screened the convoy, including HMAS Deloraine, but the I-174 slipped past the warships and, at 5.20 p.m., fired two torpedoes at a pair of transports. The first torpedo Struck the 5,000-ton Landing Ship Tank, LST 469 in the starboard side, towards the stern. The detonation completely destroyed the vessel’s steering gear and also killed twenty-six men, but LST-469 remained afloat. A few moments later the second torpedo struck the starboard side of the 5,551-ton US Army transport ship Portmar. The detonation of the Japanese torpedo set a massive fire in the Portmar’s holds, which in turn set off ammunition stored aboard the ship. The crew soon abandoned the stricken ship, and after only seven minutes the Portmar sank. Two of the escorting corvettes ineffectually depth-charged the I-174. Lieutenant Nambu goes down in history as the last Japanese submarine skipper to successfully sink a ship off the east coast of Australia, and on 20 June the I-174 was ordered back to Truk. Nambu was later reassigned as commander of the submarine aircraft carrier I-401, and American aircraft east of Truk destroyed his former command, the I-174, on 12 April 1944.7
Notes
1. Data derived from Bob Hackett & Sander Kingsepp’s http://www.combinedfleet.com/I-21.htm
2. ibid.
3. The Sinking of the Centaur, Commonwealth Department of Veterans’ Affairs, http://www.dva.gov.au
4. Christopher S. Milligan & John C.H. Foley, Australian Hospital Ship Centaur: The Myth of Immunity, (Hendra: Nairana Publications), 1993
5. The Sinking of the Centaur, Commonwealth Department of Veterans’ Affairs, http://www.dva.gov.au
6. Partly derived from Bob Hackett & Sander Kingsepp’s http://www.combinedfleet.com/I-174.htm
7. ibid.
Chapter 9
Storm From a Clear Sky
There is nothing more dreadful than crazy persons. The Japanese are a crazy nation in fighting…the Japanese are always ready to throw away their lives for a nation; they regard their lives as lightly as they do the weather.
Count Okuma, a Japanese aristocrat writing in 1906
The final occasion on which a Japanese submarine operated close to the west coast of the United States was in October 1944, after an absence by Japanese forces from American coastal waters of over two years. Following the Battle of Leyte Gulf the I-12, under Commander Kameo Kudo, set out from Japan on 4 October with orders to attack enemy commerce between the Hawaiian Islands and San Francisco.
Completed at Kawasaki’s Kobe yard in May 1944, the 2,943-ton I-12 was a Type-A2 submarine, and the only one of her class. The type was identical in all regards to the Type-Al, one of which, the I-9, had acted as a command vessel coordinating Japanese submarine activities off the American west coast in early 1942. The only difference between the I-12 and the earlier models was a decrease in power, and an extended operational range of 22,000 nautical miles at 16 knots. This made the submarine ideal for operations off the American coast.
In October 1944 the I-12 was reassigned directly to 6th Fleet and given the unenviable task of returning a Japanese submarine presence to the waters off the United States. Commander Kudo was instructed to take the I-12 from Japan directly to the waters off California and to attack merchant ship convoys. After a run along the west coast Kudo was to backtrack to Hawaii, then sail to Tahiti and finally to a point east of the Marshall Islands before returning home. The Japanese could spare only a single submarine for the operation at this stage of the war as the strategic situation inexorably deteriorated for Japan. This was in contrast to the nine Japanese submarines that had deployed along the west coast during early 1942.
On 4 October the I-12 left Kure and motored towards its fate. On 30 October Kudo came upon a lone ship in the North Pacific steaming from San Francisco to Honolulu, and he attacked immediately. The ship was the John A. Johnson, a 7,176-ton American Liberty ship loaded down with 7,000 tons of supplies, including army trucks lined up on her decks, bound for the troops fighting in the Pacific. She carried a crew of forty-one, plus twenty-eight US Navy armed guards to man her several self-defence guns and a single army officer who was in charge of the cargo. The John A. Johnson was sailing at a ponderous 9 knots, with all lights extinguished and she was maintaining a strict radio silence. At 9.10 p.m. the first torpedo struck her starboard side, tearing loose the trucks stored on deck, and knocking the gunners and crewmen off their feet. Even though dealt a crippling blow, the armed guards, unaware of how badly damaged their ship was, raced to return fire at the unseen Japanese submarine. According to the account of one of their number, Seaman Harold L. Clark:
Lieutenant Yates came up and told me to help man the number 6 gun. I proceeded to the number 6 gun, and there sighted [the] explosion just astern of [the] ship. It looked like another torpedo. The ship began to break in two.1
The crew hastily abandoned the foundering vessel, and took to the lifeboats and rafts:
We saw [an] object about three hundred feet away from us. We signaled object thinking it was another raft and it returned the signal. It came to the surface and turned out to be the submarine, and it started coming toward us.2
The John A. Johnson’s back had been broken by the torpedo detonations, and as the crew watched from their lifeboats and rafts the ship broke into two sections that stayed afloat. Kudo had dark plans for the men marooned in their little boats far out at sea. When the I-12 broke the surface the main deck-gun was immediately manned and made ready. In the meantime machine guns had been brought up from below onto the I-12’s conning tower bridge. Surging forwards, the bow of the I-12 slammed into one of the lifeboats, tumbling terrified survivors into the sea, and at the same moment a clatter of machine-gun fire poured forth from the conning tower. Japanese seamen sprayed a murderous and indiscriminate fire onto the helpless men in the lifeboats or swimming in the water, Japanese officers also taking pot shots at the sailors with their pistols. Aboard Clark’s raft they fearfully watched the approaching submarine:
About one hundred and fifty feet from us, [the] submarine machine-gunned us. I could see tracers going over our heads. We jumped into [the] water. Submarine passed by about one hundred and fifty feet. We swam back and got on the raft. Submarine circled and came back at us again.3
Men desperately attempted to row their lifeboats clear of the pirate submarine and its murderous crew. The I-12 surged through the mass of lifeboats and rafts and kept firing, ‘We dove into the water again,’ recalled Clark, as the Japanese renewed their attention on his raft. ‘This time [the] submarine hit the raft, and as it passed by they fired again with [a] machine gun, tracers hitting [the] water near me.’4 The I-12 came close enough to the men in the water for Clark to notice: ‘Five American flags were painted on the port side of the bow. Men on the submarine were yelling “Bonzi” [sic] and cursing at us.’5 About half an hour after they had attempted to murder the crew, Japanese gunners fired a fusillade of shells at the two sections of the former John A. Johnson until they caught fire, exploded and sometime around dawn the following day sank. Six merchant seamen were killed and many wounded, before darkness finally ended the Japanese attack and the I-12 submerged and
made off from the scene of the crime. It was the flames and explosions resulting from the Japanese assault on the two sections of the John A. Johnson that assisted in the men’s rescue from the ocean. A Pan American Airways airliner spotted the flames far below and managed to signal to the lifeboats, and the pilot reported what he had seen to the US Navy in San Francisco. The USS Argus rescued the men at noon the day after the attack.
The I-12 would earn her comeuppance for the sadistic murder of innocent sailors, and retribution was not long in coming. Sailing away from the west coast, Kudo headed into the mid-Pacific and reported to 6th Fleet headquarters during late December that he had managed to sink an enemy tanker and another freighter, though this claim has never been confirmed. The last anyone ever heard of Commander Kudo and the 113 other officers and men aboard the I-12 was a radio transmission sent on 15 January 1945. Kudo reported that enemy forces north of the Marshall Islands had located his submarine. No one knows what fate befell the I-12, and the Japanese noted on 31 January that the vessel had been lost with all hands sometime after the receipt of that final radio message.
Japan’s submarine construction programme eventually produced the single most extraordinary class of boats conceived by any of the combatant navies of the Second World War. The I-400-class submarines were created in order to take Fujita’s original plan to attack the United States on home ground to a devastating conclusion. Fujita’s plan was dusted off, read again and evaluated, and the problems of the September 1942 missions over the forests of Oregon analysed. Solutions were sought to make any future attacks a success.
As early as April 1942 the Imperial Navy had decided to order the construction of a class of submarine that would dwarf previous Japanese creations in order to provide a far-reaching strike capacity. The problems with Fujita’s original concept were obvious and based around the equipment the Japanese had utilized when making the attacks. The Yokosuka E14Y1 floatplane was not a dedicated bomber, but a reconnaissance plane that could be used as a bomber, capable of carrying a tiny munitions payload. The bomb load was pathetically small, and getting the aircraft in range of a ground target was largely a waste of naval resources. The aircraft was also ponderously slow, with a cruising speed of only 90 miles per hour, which although making it an ideal reconnaissance platform, also made it very vulnerable to anti-aircraft fire and enemy fighters. The E14Y1 was also virtually defenceless, armed with a single rear firing 7.7mm machine gun, so if it had encountered an enemy fighter it would in all probability have been shot down with ease. The submarines that were fitted with the E14Y1, such as the I-25, were only able to store a single aircraft inside their waterproof hangar. The only conceivable way the Japanese could have mounted a sizeable raid with these little planes would have been by gathering several submarines together off the American coast, which in itself was a waste of the submarines’ own fighting potential as they waited around for the return of their aircraft, and exposed the boats to the risk of aerial and ship attacks.
The answer to all of these problems was a single submarine large enough to both reach land targets in the United States without requiring any refuelling, and able to carry more than one aircraft. The new bombers would have to be potent weapons, able to deliver a large payload of bombs, but still retaining the floatplane characteristics enabling their operation at sea from submarines. In effect, the Japanese Navy required a submarine aircraft carrier, and this is exactly what they set about designing and constructing between April 1942 and December 1944.
Each I-400-class vessel was a monster, the largest submarines built until well into the post-war nuclear age, their size only surpassed in 1962 when the Americans commissioned the USS Lafayette. Displacing 5,223-tons surfaced, each boat was 400.3 feet in length with a beam of 39.3 feet and was powered by four diesel engines and electric motors. Atop the weather deck was a 115 feet long waterproof hanger, twelve feet wide, big enough for three specially designed torpedo bombers. In front of the hangar, bolted to the immense deck stretched a pneumatic aircraft-launching catapult eighty-five feet long, and alongside this a powerful hydraulic crane for recovering the aircraft from the sea.6 Through the Yanagi underwater trade in weapons and new technologies conducted between Nazi Germany and the Japanese, the Imperial Navy had copied the snorkel technology fitted to late-war U-boats, and these were fitted to all four I-400-class submarines. The snorkel mast, when extended above the surface of the water as the submarine cruised at periscope depth, enabled the boat to run on its diesel engines instead of batteries, producing a greatly increased underwater speed and protection from aerial detection and attack. Hugely capacious fuel tanks on each boat meant that each of these submarine aircraft carriers was capable of cruising an astounding 35,500 nautical miles at 14 knots before the tanks ran dry, in other words giving the Japanese skipper the ability to circumnavigate the globe one and a half times. The huge range of these vessels meant that for the first time in the war the Japanese Navy had a machine capable of not only crossing the Pacific to attack the west coast of the United States, but also, in theory, of crossing into the Atlantic via Cape Horn and unleashing air strikes against New York or Washington DC, and both cities were later seriously considered by naval planners in Tokyo for attacks. The I-400-class submarines were capable of a top surface or submerged snorkel speed of 18.7 knots, or if fully submerged and running on electric motors 6.5 knots. Radar and radar detectors, though not up to the German standard, were fitted to all four boats of the class. Although submarine aircraft carriers the I-400-class boats were more than capable of fighting like any other submarine types, having eight torpedo tubes (and twenty torpedoes) and an improved 140mm 50 calibre deck-gun. Improved anti-aircraft defences increased each boat’s chances of standing off an aerial assault, with a 25mm cannon mounted on the conning tower, and three triple barrelled 25mm cannon located on top of the aircraft hangar, giving a total of ten guns. With a maximum diving depth of almost 330 feet, each boat took slightly under one minute to crash-dive.7
Such superb and powerful vessels required an equally superb and capable aircraft type, and here the Japanese also excelled. Each I-400-class submarine was designed to carry a maximum of three Aichi M6A1 Seiran torpedo bombers. Seiran can be translated as ‘Storm from the sky’,8 and these aircraft were no ponderous reconnaissance types but sturdy birds of destruction. Still floatplanes, each monoplane measured thirty-five feet in length, with a wingspan of forty feet. Designed by Toshio Ozaki, chief engineer at Aichi, the Seiran had to conform to a series of guidelines laid down by the Imperial Navy as they sought the perfect plane for their new submarines. In late 1942 Ozaki began developing the aircraft that the navy specified must have been capable of carrying a maximum bomb load consisting of a single 1,288-lb (800kg) aerial bomb or torpedo. In the light of the desperate position Japan was in by late 1944, if a kamikaze mission was called for the floats could be detached and the fuel and bomb load increased for a one-way mission against the enemy. The navy also stipulated that the aircraft must be capable of a top speed of 294 miles per hour with floats, or 347 miles per hour with the floats detached. Under normal, non-kamikaze, operating conditions each Seiran had a range of 654 miles, which meant that the ‘mother’ submarine could sit some way off from the enemy shore when launching and recovering its air group, instead of having to come close inshore to launch and then sit vulnerably on the surface awaiting an aircraft’s return from its sortie.
The first prototype Seiran was completed in October 1943, and several others followed. The navy, however, was overjoyed with the performance of the prototype aircraft and ordered full production before testing had been completed at Aichi in early 1944. This decision was probably hastened by the deteriorating Japanese naval situation, and the necessity of getting the new submarines and aircraft into action as soon as possible. This was to prove to be no easy task as American bombing raids and even an earthquake, which completely shut down production at Aichi by March 1945, hampered production of the aircraft. In the end Aichi engineers
managed to cobble together twenty-six Seiran torpedo bombers (including prototypes) and a pair of land-based trainers, the M6A1-K Nanzan. The navy no longer required a large number of Seiran aircraft as they had been forced by the weakening of Japan’s economy to scale back the number of I-400-class submarines under construction. The I-400 was ready for service on 30 December 1944, and the I-401 followed a few days later. I-402’s duties were changed from being an underwater aircraft carrier, and instead she was refitted as a submarine fuel tanker. Two other boats, I-404 and I-405 were abandoned on the slips and not completed before the Japanese surrender.
Although each I-400-class submarine’s complement was listed officially as 145 men, on operations up to 220 crewmen were carried aboard in order to make the dispatching and recovering of the aircraft as efficient an operation as possible. The Seiran aircraft were stored inside the huge hangar with their floats detached, and their wings and tails folded up. Each well-trained team of aircraft technicians and mechanics could assemble a single aircraft in around seven minutes, ready for launching. All three torpedo bombers could be assembled, fuelled and fitted with either torpedoes or aerial bombs, attached to the launching ramp and catapulted away in about forty-five minutes (close enough to the original Japanese Navy stipulation of thirty minutes). In order to maintain the air group while the submarine was at sea a special compartment was located inside the pressure hull beneath the hangar where engineers could test aircraft engines and maintain the airframes. Beside this was the aircraft magazine, containing four aerial torpedoes, fifteen bombs and ammunition for the aircraft’s cannon and machine guns.9