The light Japanese aircraft carrier HIYO was one of three sunk in the Battle of the Marianas, or in American accounts, the Battle of the Philippine Sea, the so-called "Turkey Shoot". In this battle, the HIYO ("Flying Departing Hawk") was part of Vadm Ozawa Jisaburo's MOBILE FLEET and with her sister JUNYO and the light carrier RYUHO was assigned to Radm Joshima Takagi's CarDiv2. At the time commanded by Captain Yokoi Toshiyuki, the HIYO was sunk by the sunset air attack from TF 58 the afternoon of 20 June 1944. In S.E. Morison's History of U.S. Naval Operations Vol VIII NEW GUINEA AND THE MARIANAS is found the following account.
The account begins on p 295 and indicates that four Avengers armed with torpedoes from BELLEAU WOOD led by Lt. George Brown attacked HIYO. Though his plane was hit and damaged and forced his radioman and gunner to bail out, Brown pressed his attack and seems to have scored a torpedo hit as the carrier turned hard to port. His wingman's torpedo missed, but a third fired by Lt. Omark is judged to have been a certain hit also [amidships]. Brown pulled out, but badly wounded, did not make it home and apparently crashed. "The two crewmen of this (Brown's plane) who bailed out...became interested spectators of HIYO's last moments as they floated in the water....fires spread rapidly over the carrier until she was burning from stem to stern. Three violent explosions were felt by the swimmers, and several smaller explosions followed. As darkness descended, HIYO, down by the bow so that her PROPELLERS (Italics mine) were out of the water, cast a brilliant light on the surrounding waters. About two hours after the hit she disappeared..."
This account appears in paraphrased or abbreviated form in nearly all western works on the subject (Most recently in excellent detail in T Y'blood's RED SUN SETTING). However, one exception appears in the RISING SUN by John Toland, giving a fascinating account from an interview with a Japanese HIYO survivor, and reads as follows:
p571 (paperback version):"At his machine gun in the stern of HIYO, Chief Petty Officer Mitsukuni Oshita head the cry "Torpedo coming!" (during the air attack). He began to count. At 12 he knew the torpedo had missed, and relaxed. An explosion jarred HIYO. Oshita had counted too fast. A second torpedo rocked the carrier. Fires spread from deck to deck and all power went off. Dead in the water, she began listing to port and the word went out to abandon ship. At the extreme stern, Oshita and a dozen others heard nothing and refused to abandon HIYO without a definite order. The ship settled rapidly. Water gurgled up toward Oshita's machine gun, and he and his companions started for the rail. "Wait!" Their commander, a young ensign, drew his sword threateningly."Sing Umi-Yukaba!"....the cowed men sang until the water reached their knees, then broke past the officer and over the side. Oshita looked back. Fire belched out of the carrier. Spotlighted in the red glare, the ensign clung to the stern rail, sword in hand, still singing. He disappeared as the great bow reared high, and Oshita had to swim desperately to avoid the suction. "The ship is going down!" someone shouted. Oshita turned around. HIYO was sticking up like the finger of a giant. She plunged out of sight with a "horrible sigh" as if, thought Oshita, she were saying,"This is the end".
At a glance it is immediately obvious that the Oshita account flatly and continually contradicts the report of the bailed out American fliers reported by Morison, insisting on the HIYO sinking by the stern, not by the bow, but agreeing in the detail of a sharp-angle plunge. Toland's skill with Japanese makes it highly unlikely that he transposed the words "bow" and "stern". [Which in Japanese are more akin to "head/neck" and "feet" and not easily mixed].
At first glance, this appears to be yet another example of how accounts of Imperial Japanese Navy events can vary widely with no real consensus in sources. On closer examination however, the HIYO paradox is found to represent the tip of a larger overlooked gap in the record. Namely, the simple fact that HIYO's overall fate is discussed lightly, if at all, by the extant sources. It is the purpose of this inquiry to add as much flesh as possible to the present skeleton of facts and to provoke further research among those of similar interest with opportunity to do so.
To summarize the available body of evidence: at approximately 1720-1740 hours (Tokyo time) the HIYO came under aerial bomb and torpedo attack from TF 58. All accounts, American and Japanese, agree that one, probably two air torpedoes struck the HIYO and rendered her unnavigable. In addition, U.S. Navy attack reports claim bomb hits as well, and given the paucity of IJN records on the HIYO, this does not seem unlikely. In any case, the HIYO went dead in the water and began listing to port. Damage control teams went to work, and the vessel did not settle quickly. However, at 1926 hours the HIYO was rocked by a tremendous explosion. (The Japanese believed a submarine torpedo was responsible; rattled as they had been by the sinkings of both TAIHO and SHOKAKU by submarine the prior day. However, no submarine was present). Most likely, this was an internal explosion induced by the ever-fatal leaking av-gas and unrefined petroleum fumes. Following this, the burning carrier then settled rapidly, and at 1932 slipped under the waves. This brings us to the question raised earlier: which account of the sinking, if either, is correct? Though no definitive answer is forthcoming, the instinctive response is to assume the eyewitness report of the HIYO survivor is closer to the facts. Can this be shown to be probable, rather than merely possibly unwarranted assumption? I believe it can.
The clue lies in the albeit scanty official Japanese reports on the HIYO's loss. The first one that should be noted is the Detailed Action Report of Ozawa's Mobile Fleet. In the document titled First Mobile Fleet Classified No. 1048 (5 September 1944) [WDC 161517] is listed the Detailed report of the A-GO Operations.
Under damage to ships in the battle of 20 June: "From 1730 (Tokyo time) on the 20th, the 1st Carrier Division, 2nd Carrier Division, Diversion attack forces, and supply forces incurred enemy air attack:
HIYO : Ship (aircraft carrier) suffered combined bombing and torpedo attack; one torpedo hit, making steerage impossible. While drifting about, ship again incurred torpedo attack by enemy submarine. One torpedo hit, large conflagration broke out within the ship, and she finally sank at 1932 hours."
One fact is particularly worthy of attention, and that is "steerage impossible". This implies very strongly that the rudder was damaged by the torpedo hit, though not necessarily by a hit aft. But the next source we have is more explicit. It is also contemporary, being taken from the diary of Admiral Matome Ugaki. The entry for 22 June, 1944 page 416 reads:
"One torpedo struck HIYO on HER STERN (italics mine) at the time of the air raid. She was rendered incapable of navigation and was struck again with one bomb, set on fire, and sunk."
The similarity to the official report, which Ugaki doubtless had in some form, is clear, but that the torpedo hit the stern, disabling steering, is made explicit. He also suggests that TF 58 claims of bomb damage are justifiable as well. Another official Japanese source, the BKS volumes of the History of the War published by the Japan Defense Agency, surprisingly add nothing extra to these accounts beyond that of the Mobile Fleet report quoted.. Nevertheless, from the foregoing it seems possible to assert that HIYO sank by the stern, not the bow, for the following reasons:
[1] The direct testimony of the eyewitness, Chief Petty Officer Oshita, Mitsukuni, as quoted by John Toland's RISING SUN.
[2] The record of Admiral Ugaki's diary, which states the torpedo hit the stern and disabled steering. Water would be naturally expected to be dragging down the aft as a result.
[3] The Mobile Fleet War Diary which gives direct confirmation of loss of steering by the HIYO, and thus supporting evidence that Ugaki's account is correct.
[4] The paradoxical report of downed U.S. fliers awaiting rescue claiming HIYO went down by the bow is possibly mistaken and can be explained. Tokyo time, used in the Japanese report, was an hour behind local or Marianas time. Hence, it is 2032, 8:32 PM when HIYO sinks. The sea must have been quite dark by then. Also, since the two men watching had bailed out during the initial attack, if HIYO did not go dead in the water instantly, she would have moved off or drifted a bit away. In such twilight, if not darkness, a blazing ship going down would be silhouetted in surreal contrast to the night sky. Both Japanese and American observers agree on the detail of a "tilted up" final plunge. It does not seem unreasonable to suggest that an upended hull could have appeared as the stern to the American fliers when it was actually the bow. Especially when the likely distance from the sinking and the hour are taken into account. The propellers of course, would have to be mistaken (unless she broke in half?). In any case, the HIYO survivor was not only probably more inclined to watch the details of his ship's sinking, he was much closer.
From the proceeding collation of evidence, though proof remains inconclusive, it seems unlikely that John Toland has mangled Oshita's account, nor has HIYO's survivor erred in memory. Thus, in all probability, what happened was this---Hiyo was hit in the port quarter by a torpedo that disabled her steering; she may then have been hit by another torpedo in the engine room as many claim and her stopping also suggests. The carrier began burning and drifting, and listing to port, and inexorably, began to settle aft where the hole in the stern was. Both Japanese and Americans are witnesses to the final moments, the former presumably much closer. At 2032, well after sunset, the end came, and Hiyo upended and sank. But the `end up' was the bow, not the stern, though it may have looked that way in the darkness and at a distance to the Americans. This, I believe, is the most reasonable likelihood.
One final note should be made. The paucity of HIYO's story goes beyond the manner of her sinking. None of the books on the battle mention the numbers of crew lost or how many survivors were rescued. For the sake of the historical record and those interested, those facts are included here. Her commander, Captain Yokoi Toshiyuki survived to become Chief of Staff of Ugaki Matome's Fifth Air Fleet in spring of 1945. Despite the fires and explosions, most of HIYO's crew also survived and were rescued by the destroyers SHIGURE, HAMANAMI, AKISHIMO, HAYASHIMO, HAMAKAZE, and MICHISHIO while NAGATO and MOGAMI stood guard. However, 250 officers and men went down with her. Any readers with additional knowledge about the questions raised or damage to the HIYO are encouraged to contact the author of this article to help complete the carrier's story. Any contribution would be greatly appreciated. Commentary and discussion would be welcome.
