(Hiyo by Takeshi Yuki-"Color Paintings
of Japanese Warships")
IJN Hiyo: Tabular Record of
© 1998/2006 Anthony P. Tully
Revised Enhanced Edition:
© 2013 Anthony P. Tully and Gilbert Casse
30 November 1939:
Kobe. Laid down at Kawasaki Heavy Industries Shipyard as the 27,500-ton passenger liner IZUMO MARU for Nippon Yusen Kaisha (NYK).
10 February 1941:
Purchased by the Department of the Navy to be converted to an auxiliary aircraft carrier.
24 June 1941:
Launched as IZUMO MARU.
31 July 1941:
Christened at Kobe as IZUMO MARU.
15 November 1941:
31 July 1942:
Captain (later Rear Admiral) Beppu Akitomo (38) (former CO of carrier SORYU) is appointed Chief Equipping Officer.
Re-named and placed in commission as HIYO (“Flying Falcon”). Attached to Kure Naval District. Following the loss of four fleet carriers at Midway, HIYO is re-designated as a regular carrier. Assigned to Rear Admiral (later Vice Admiral) Kakuta Kakuji's (39) (former CO of battleship YAMASHIRO) CarDiv 2, Third Fleet also consisting of sister-ship JUNYO and light carrier RYUJO. That same day, Captain Beppu is appointed Commanding Officer (CO).
For general particulars layout as completed and subsequent alterations see new:
HIYO Data page
E August 1942:
10 August 1942:
During her trials, a maximum speed of 25.63 knots is reached.
11 August 1942:
Arrives at Kure.
12 August 1942:
Receives the flag of Rear Admiral Kakuta Kakuji, ComCarDiv 2, Third Fleet.
13 August 1942:
Arrives at Hashira-jima.
Mid August-September 1942:
14 September 1942:
Inland Sea. Undergoes intensive training exercises to her air group with sister-ship JUNYO, DesDiv 16's YUKIKAZE (August only), DesDiv 19's ISONAMI and DesDiv 6's IZANUMA (September only).
Off Saeki. HIYO's air group is part of a major training exercise.
4 October 1942:
Rear Admiral Kakuta's CarDiv 2 departs Saeki for Truk, Central Carolines escorted by DesDiv 19's ISONAMI and DesDiv 6's IZANUMA. HIYO's aircraft complement consists of 21 A6M2s, 18 D3A1s and 9 B5N2s.
9 October 1942:
Arrives at Truk. Assigned to Main Unit Advance Force (CarDiv 2, Third Fleet).
11 October 1942:
Departs Truk in the preliminaries to the Battle of Santa Cruz in Rear Admiral (later Vice Admiral) Kakuta Kakuji's (39) (former CO of YAMASHIRO) Advance Force's CarDiv 2's also consisting of sister-ship JUNYO and DesDiv 15's HAYASHIO and KUROSHIO.
CarDiv 2 is accompanied by Rear Admiral (later Vice Admiral) Abe Hirohaki's (39) Vanguard Force: BatDiv 11's HIEI and KIRISHIMA, CruDiv 7's SUZUYA, CruDiv 8's TONE and CHIKUMA, DesRon 10's NAGARA, DesDiv 10's MAKIGUMO, KAZAGUMO, AKIGUMO and YUGUMO and DesDiv 17's URAKAZE, TANIKAZE and ISOKAZE.
Abe and Kakuta's forces are followed by Nagumo's Carrier Strike Force's CarDiv 1's SHOKAKU, ZUIKAKU and ZUIHO, CruDiv 7's KUMANO, DesDiv 16's AMATSUKAZE, HATSUKAZE, TOKITSUKAZE and YUKIKAZE, DesDiv 4's ARASHI, MAIKAZE and DesDiv 61's TERUZUKI.
16-17 October 1942:
Rear Admiral Kakuta's CarDiv 2 is ordered to launch an airstrike on the US transports moored off Lunga Point, Guadalcanal. In the night of 16 'Oct, HIYO and JUNYO head south to their launching spot, 180 miles N of Henderson Field.
- At 0515, 18 B5N2s (9 from each carrier), with a 800kg bomb, escorted by 18 A6M2s (9 from each carrier) take off and head to the target. However one B5N2 from JUNYO aborts mission due to mechanical trouble and returns to its carrier.
- At 0700, Florida Island is sighted and both Air Groups commanders decide to attack USS AARON WARD (DD-483) and LARDNER (DD-487), both ships on a shore bombardment mission targeting Japanese supply dumps.
- At 0727, HIYO's 9 B5N2s target AARON WARD but score no hits, losing one B5N2 from AA fire. Shortly afterwards, JUNYO's 9 B5N2s target LARDNER but are engaged by VMF-121 F4F “Wildcats”. In the ensuing battle, 3 B5N2s are shot down and 2 damaged.
- At 0735, without scoring any hit on LARDNER, 3 additional B5N2s are shot down by the F4Fs and AA fire, for the loss of only one F4F, shot down by the escorting A6M2s. Finally, one damaged B5N2 ditches near Rekata Island and two others land at Buin. Of the nine JUNYO's B5N2s, only one returns safely (the one that aborted mission). The first operation of CarDiv 2 is a total failure.
21 October 1942:
While operating off Guadacanal prior to the Battle of Santa Cruz, a fire breaks out in the starboard generator room. Considerable damage to the condenser is caused and the carrier is slowed to 16 knots.
22 October 1942:
Admiral Kakuta's flag is transferred to JUNYO as well as 3 A6M2s, 1 D3A1 and 5 B5N2s. Later in the day, HIYO returns to Truk on her port engines for emergency repairs, escorted by DesDiv 19's ISONAMI and DesDiv 6's IZANUMA.
23 October 1942:
HIYO's remaining air group consisting of 16 A6M2s and 17 D3A2s takes off to Rabaul, New Britain.
24 October 1942:
HIYO's fighters provide air cover for the landing forces attacking Guadalcanal.
26 October 1942:
Arrives at Truk for repairs.
1 November 1942:
Part of HIYO's air group is transferred to Buin, Bougainville.
11 November 1942:
Rabaul. HIYO's remaining aircraft transfer to Truk.
13 November 1942:
`Minor' damage attested while at Truk. (See Note 1)
13-14 November 1942:
Buin. HIYO's aircraft serve as air cover to the high-speed convoy sent to Guadalcanal.
27 November 1942:
`Minor' damage again listed while at Truk.(See again, Note 1)
30 November 1942:
Captain Beppu is relieved by Captain (later Rear Admiral) Sumikawa Michio (45) (former CO of seaplane tender MIZUHO) as commanding officer.
5 December 1942:
Reassigned to Mobile Force. Departs Truk for Kure escorted by DesDiv 16's YUKIKAZE and DesDiv 11's HATSUYUKI and SHIRAYUKI.
11 December 1942:
Arrives at Kure from Truk via Saeki.
18 December 1942:
Air group returns to Japan, arriving at Saeki base to rejoin the carrier.
29 December 1942:
Repairs complete, departs Kure.
15 January 1943:
Assigned to Mobile Force, Stand-by Force (CarDiv 2, Third Fleet).
In and out of Tokuyama, Yamaguchi Prefecture frequently, remaining in the Inland Sea.
26 February 1943:
Enters drydock at Kure. Four Type 96 triple 25mm AA guns are added as well as two related Type 95 directors. The carrier is also fitted with a second Type 21 air search radar placed on the port side of the hull, outboard of the rear elevator.
4 March 1943:
Undocked. Departs Kure and resume movements between Kure and Tokuyama.
22 March 1943:
Reassigned to Main Unit Mobile Force. Departs Saeki for Truk with sister-ship JUNYO, DesDiv 61's SUZUTSUKI and HATSUZUKI, DesDiv 15's KAGERO and DesDiv 27's YUGURE. HIYO's air group consists of 27 A6M2s and 12 D3A2s .
27 March 1943:
Arrives at Truk.
1 April 1943: Operation "I-GO" - The Reinforcement of Rabaul:
Assigned to contribute aircraft to "I" Operation activated by Commander-in-Chief Yamamoto Isoroku this day. Aircraft from CarDiv 1's ZUIKAKU and ZUIHO are detached to reinforce the 11th Air Fleet's base at Rabaul and aircraft from CarDiv 2's HIYO and JUNYO to reinforce the base at Ballale Island, near Buin.Vessel itself remains at Truk.
12 April 1943:
Subjected to bombing but escaped with minor damages. (See Note 2)
3 May 1943:
Assignment changed to Advance Force, Mobile Force.
17 May 1943:
In response to the Attu invasion, Admiral (Fleet Admiral posthumously) Koga Mineichi (34) departs Truk with BatDiv 1's MUSASHI, BatDiv 3's HARUNA and KONGO, CarDiv 2's HIYO, CruDiv 8's TONE and CHIKUMA and DesDiv 24's UMIKAZE, DesDiv 27's ARIAKE and SHIGURE and DesDiv 61's HATSUZUKI and SUZUTSUKI.
20 May 1943:
Alerted by Ultras, LtCdr Eugene T. Sands' (USNA '30) USS SAWFISH (SS-276) picks up the task force on radar but the submarine is unable to attack.
21 May 1943:
Reassigned from Advance Force to Main Body of Mobile Force.
22 May 1943: Operation "Kita" (North):
USS TRIGGER (SS-237) sights the task force off Tokyo Bay, but is unable to attack. The task force arrives safely at Yokosuka-Tokyo Bay. Carriers ZUIKAKU, SHOKAKU and ZUIHO and light cruisers AGANO and OYODO join the task force; CruDiv 7's KUMANO, MOGAMI and SUZUYA also arrive from Tokuyama. Before this powerful force can depart for a counterattack against the Aleutians, Attu falls to American forces.
25 May 1943:
Arrives at Kisarazu, Chiba Prefecture.
29 May 1943:
Operation Kita is canceled.
2 June 1943:
Arrives at Yokosuka.
5 June 1943:
Transfers to Kisarazu.
7 June 1943:
Transfers to Yokosuka.
10 June 1943:
1400: Flying the flag of ComCarDiv 2 Rear Admiral (later Vice Admiral) Sakamaki Munetaka (41) (former CO of light carrier HOSHO) - departs Yokosuka for Truk escorted by destroyers ARIAKE and YUGURE. However, prior to 2000 hours in position bearing 64 degrees 17 miles from Miyake Island Cdr (later Rear Admiral) Roy S. Benson's (USNA '29) USS TRIGGER (SS-237) sights the carrier and her two escorts. Benson fires six torpedoes. One prematures, two miss ahead, but three hit the starboard side at 1852 hours. One hits forward of the bridge, only to fail to explode and break in half, but two torpedoes do detonate; one in the bow under the hawse pipe, and the other hits No. 1 boiler room on the starboard side. The explosion also shatters the bulkhead dividing No.1 from No.2 boiler room on the port side which promptly flood. All of No.1 and half of No.2's black gang perish. The carrier goes dead in the water and settles by the bow. Slow leakage even threatens to flood No.3 boiler room aft and water begins to enter the lower hangar deck forward. However valiant damage control keeps her afloat all through the long night that follows with a bucket brigade slowly draining the water from the lower hangar. During it, a “friendly fire” incident ensues at 1937 when HIYO's nervous gunners open fire and slightly damage one of the destroyers gliding past, killing two. The next morning, light cruiser ISUZU en-route to Tokyo Bay arrives to tow, but since 0800 the carrier is already back under her own power using No.3 boiler room, and the tow attempt hinders more than it helps. HIYO returns to Tateyama by midnight of the 11th using two screws and crawling at 6 knots escorted by ISUZU and destroyers ARIAKE and YUGURE. (Note 3)
12 June 1943:
Transfers to Yokosuka at 1053. Here the bottom of the bow of the ship actually touches bottom and HIYO grounds there for the time being as emergency pumping out and repairs continue.
13 June 1943:
CoS of ComCardiv 2 advises that flag will shift to RYUHO on the 15th, and upon reaching Truk on the 21st, will shift finally to JUNYO.
15 June 1943:
While their ship is under repair, HIYO's aircraft (21 A6M2 fighters, 9 B5N2 attack planes, 18 D3A2 dive bombers) and crew are assigned to temporary duty on the light carrier RYUHO. As it is not possible to load all aircraft on RYUHO, HIYO's fighters fly to Truk via Iwo Jima and Tinian.
Caisson to facilitate repairs and refloating is placed in position, and once done, pumping out of the carrier is expected to take a week. At this time the damaged sections are underwater and inspection is impossible.
29 June 1943:
Enters drydock for repairs at Yokosuka.
31 August 1943:
HIYO's crew returns to their ship without aircraft from the RYUHO as repairs are near completion.
1 September 1943:
Captain Sumikawa is relieved by Captain (later Rear Admiral) Furukawa Tamotsu (43) (former CO of seaplane tender CHITOSE) as commanding officer.
15 September 1943:
Leaves Yokosuka drydock, repairs being completed. HIYO's light AA armament is bolstered by the addition of four Type 96 triple 25mm AA mounts, two of these are mounted on the stern and the others placed in front and behind the island. 12 Type 96 single 25mm AA mounts are also added, some of which are portable and can be mounted on tie-down points on the flight deck. The same day, the aircraft of CarDiv 2 are staging on land at Tusiki and Iwakuni.
5 October 1943:
Aircraft of CarDiv 2 fly south to Singapore for training , and soon HIYO is ordered south to rejoin them.
7 October 1943:
At Yokosuka HIYO fire-fighting and flight deck extinguishing sprays are tested. (This incidentally is the only extant aboard ship photograph yet confirmed for HIYO).
29 October 1943:
Arrives at Kure from Yokosuka.
1 November 1943:
Singapore. HIYO's air group is reconstituted with 24 A6M2s, 18D3A2s and 9B5N2s. Training continues intensively throughout that month.
24 November 1943:
Departs Inland Sea for Singapore via Taira-Jima, Ryukyus and Manila with light carrier RYUHO and DesDiv 21's WAKABA, HATSUHARU and HATSUSHIMO.
E 27 November 1943:
Calls at island of Heigun To, Inland Sea, Yamaguchi Prefecture. Departs later that same day for Manila.
29 November 1943:
Arrives at Manila, Luzon for overnight stay.
30 November 1943:
Departs for Singapore.
3 December 1943:
Arrives at Singapore, RYUHO and screen still in company. Air groups are transferred to the carriers.
9 December 1943:
Assigned to aircraft ferry duty, departs Singapore for Truk with light carrier RYUHO and DesDiv 21's WAKABA, HATSUHARU and HATSUSHIMO.
14 December 1943:
Arrives at Tarakan, Borneo.
16 December 1943:
18 December 1943:
Arrives at Palau, Western Carolines.
20 December 1943:
22 December 1943:
Arrives at Truk. That same day, HIYO and RYUHO are refueled by auxiliary oiler NICHIEI MARU. HIYO's air group is detached to Truk.
27 December 1943:
Departs Truk for Saipan, Marianas ferrying aircraft with light carrier RYUHO, DesDiv's 6 HIBIKI and INAZUMA and DesDiv 17's HAMAKAZE.
29 December 1943:
Arrives at Saipan. Departs that same day for Kure with RYUHO, HIBIKI, INAZUMA and HAMAKAZE.
E end of December 1943:
HIYO's air group is transferred to Kavieng, New Ireland.
2 January 1944:
Arrives at Kure, still accompanied by RYUHO.
25 January 1944:
HIYO's air group is transferred to Vunakanau Airfield, Rabaul.
15 February 1944:
Captain Furukawa is relieved of command. Captain (later Rear Admiral) Yokoi Toshiyuki (46) takes his place as commanding officer the next day.
19-21 February 1944:
After losing more than half of his fighting power, the remnants of CarDiv 2's air group, consisting of 15 A6M2s, 14 D3A2s and 8 B5N2s, are transferred to Truk. HIYO's air group is subsequently disbanded.
2 March 1944:
HIYO's aircrew depart Truk for Japan without their aircraft.
10 March 1944:
Creation of the 652nd Air Group assigned to CarDiv 2. At full strength, the Air Group should consist of 81 fighters, 36 dive-bombers and 27 attack planes, totaling 144 aircraft.
1 April 1944:
The 652nd Air Group still is not at full strength and only consists of 30 A6M2 and 13 A6M5 fighters and 4 D3A2 dive-bombers.
In Iwakuni-Kure area throughout month. Engaged in intensive training with the 652nd Air Group.
11 May 1944:
Departs Saeki, Japan for Tawi Tawi, Philippines via Okinawa with CarDiv 2's JUNYO and RYUHO and CarDiv 3's ZUIHO, CHIYODA, CHITOSE super-battleship MUSASHI and DesRon 11's AKISHIMO and HAYASHIMO, DesDiv 4's MICHISHIO, NOWAKI and YAMAGUMO, DesDiv 27's SHIGURE and DesDiv 32's TAMANAMI. CarDiv 2 carries a still incomplete Air Group No. 652 consisting of 135 aircraft: 27 A6M2 fighters – to be used in a fighter-bomber role, armed with a 250kg bomb – 53 A6M5 fighters and 55 dive-bombers and attack planes.
12 May 1944:
Arrives at Nakagusuku Bay, Okinawa. Departs later in the day for the Mobile Fleet operating base at Tawi Tawi.
16 May 1944:
Arrives at Tawi Tawi and joins Mobile Fleet of Admiral Ozawa.
E May-June 1944:
Tawi-Tawi. Engaged in training but only a few times due to the presence of US submarines and the lack of an airfield in the area.
13 June 1944: Operation "A-GO" - The Battle of the Philippine Sea:
In Tokyo, the CINC, Combined Fleet, Admiral Toyoda Soemu, (33) (former CO of HYUGA), sends out a signal that activates the A-GO plan for the Defense of the Marianas.
At 0900, Ozawa's Mobile Fleet departs Tawi Tawi (less Operation "Kon's" BatDiv 1, CruDiv 5 and screen) for Guimaras near Panay Island, Philippines. HIYO is in Rear Admiral Joshima Takatsugu's (40) Force "B" also consisting of CarDiv 2's JUNYO and RYUHO, BatDiv 1's NAGATO, CruDiv 7's MOGAMI, DesRon 2's HAYASHIMO, DesDiv 4's MICHISHIO.
At 1000, LtCdr (later Cdr) Marshall H. Austin's (USNA '35) USS REDFIN (SS-272) on station outside the anchorage, sights and reports the fleet departing.
14 June 1944:
Guimaras. Refuels from the 2nd Supply Force oilers GENYO and AZUSA MARUs.
15 June 1944:
At 0800, the Mobile Fleet departs Guimaras through the Visayan Sea. At 1622, LtCdr (later Captain) Robert Risser's (USNA '34) USS FLYING FISH (SS-229) sights the Mobile Fleet exiting the San Bernardino Strait. At sunset, he surfaces and reports the contact.
Ozawa's forces refuel from the 1st Supply Force oilers HAYUSUI and NICHIEI, KOKUYO and SEIYO MARUs.
Forces “A” and “B” deploy 100 miles behind Vice Admiral Kurita Takeo's (38) former CO of KONGO) Vanguard Force "C.”
17 June 1944:
In the morning CarDiv 2's screen is reinforced by destroyers NOWAKI and YAMAGUMO.
At 1800 CarDiv 2' s screen is reinforced by destroyers SHIGURE, SAMIDARE, AKISHIMO and HAMAKAZE detached from 1st Replenishment tanker group.
At 2000, LtCdr (later Rear Admiral) Herman J. Kossler's (USNA '34) USS CAVALLA (SS-244) sights the Mobile Fleet in the Philippine Sea and reports its movement after surfacing later that evening.
18 June 1944:
At 2100, Ozawa splits the Mobile Fleet. Forces “A” and “B” proceed southward. The Vanguard Force “C” proceeds due east.
19 June 1944:
CarDiv 2's 652nd Air Group consists of 53 A6M5 fighters, 27 A6M2 fighter-bombers, 15 Nakajima 'Tenzan' B6N2 “Jill” attack planes, 11 Yokosuka Type 2 'Suisei' D4Y1 “Comet” and 29 D3A2 dive-bombers. CarDiv 2 doesn't take part in the first two airstrikes (So-called Raid I and Raid II.)
At 0950, CarDiv 2's first airstrike (the third of the day) is launched, consisting of 25 A6M2 fighter-bombers, 7 B6N2 torpedo-equipped escorted by 15 A6M5 fighters. During their outbound leg, they are redirected towards a new position but only about 20 aircraft receive the radio-message and duly change their course, the other aircraft, after failing to spot Task Force 58, return to their respective carriers. The airstrike, hence reduced to a mere 20 aircraft, fails to score any hit for the loss of 7 A6Ms.
Ozawa orders a fourth strike to be launched totaling 70 aircraft to which HIYO contributes 18 D3A2s escorted by 8 A6M5s, the first aircraft taking off at 1015. However, that airstrike is, once again, a complete failure as the planes are instructed to fly to position “15 Ri”, a wrong spot where TF 58 is absent. After circling for 30 minutes in vain, HIYO's aircraft head to Guam and arrive there at the same time as a USN aircraft raid. In the ensuing air battle, 4 A6M5 and 4 D3A2 are shot down by the F6Fs “Hellcat” for the loss of 6 “Hellcats”.
To summarize, the Mobile Fleet has launched that day 374 aircraft, including floatplanes, in four raids against Admiral Raymond A. Spruance's (USNA '06) Task Force 58. In the "Great Marianas Turkey Shoot", Ozawa has lost 244 planes in the raids. Spruance has lost 22 aircraft in the fighting including some to flak on Guam. The 652th Air Group is reduced to 46 aircraft – 19 A6M5, 19 A6M2 and 8 B6N2 – to be compared to an initial strength totaling 135 aircraft.
20 June 1944:
On the second day of Battle of the Marianas, TF-58 aircraft attack Ozawa's Mobile Fleet. HIYO while sailing with JUNYO and RYUHO, covered by NAGATO and MOGAMI with eight destroyers in screen (MICHISHIO, AKISHIMO, HAYASHIMO, SHIGURE, SAMIDARE, HAMAKAZE, NOWAKI, and YAMAGUMO) at 1740 learns of enemy aircraft approaching from the east. Swings out to launch two Tenzan smoke screen planes. Because of this, falls 6,000 meters behind JUNYO and is caught relatively open at 1745 when enemy dive-bombers and torpedo planes suddenly appear overhead and make a coordinated attack. One small bomb dropped by a plane from either USS ENTERPRISE's Air Group 10 or USS LEXINGTON's Air Group 16 grazed the foremast and explodes above the top of the bridge, showering it with fragments. Captain Yokoi is wounded in the left eye, and the Navigator and Air Officer and nearly all bridge personnel killed. Another bomb is reported to have exploded on the flight deck. Just afterward six torpedo planes from USS BELLEAU WOOD Air Group 24 drove in for an attack (U.S. records say it was four planes led by Lt (jg) George Brown, later MIA). Two were shot down, and three dropped their weapons too far away, but one badly hit and burning TBF "courageously closed to most favorable angle and range" and dropped his torpedo which struck the starboard engine room. The burning plane then hurtled by the island and was claimed to be seen to crash into the sea. (Note 4)
The carrier listed 9 degrees to starboard, but continued to steam on her port shaft for undetermined time. Her sister carrier JUNYO closed for a brief period, but was advised to proceed. Unfortunately the port engine soon stopped and HIYO went dead in the water; yet seemed in no danger of sinking. NAGATO was ordered to reverse course and return to the scene prepared to tow. However, allegedly shortly before sunset (sunset was 1817 hours), there was a large explosion that erupted from the port side aft of amidships and reportedly blew out both elevator platforms to fall back in their wells. A torpedo from an enemy submarine was believed responsible. (Note 5) This explosion damaged the main switchboard panel and stopped all power generation. Fire broke out. Leaking gas fed the conflagration and flames engulfed the whole rear of the ship. Destroyer MICHISHIO closed the port quarter to assist, but the fire raged and explosions mounted with increasing damage. The HIYO began to settle by the stern, returned to an even keel and then commenced listing to port, which was indicative of the force of the major explosion that had ripped through her earlier. With Captain Yokoi wounded and dazed, Abandon Ship was directed by XO Shigaki Kenkichi (50). Destroyer AKISHIMO came alongside the starboard bow to take the Imperial Portrait and survivors off directly. The ensign was lowered and the men began an orderly abandonment as darkness fell.
Sunk: At 1932 mortally stricken, and settling fast now, HIYO rears her bow skyward and sinks stern first. Lost with her are 35 officers and 212 petty officers and men. Injured Captain Yokoi had intended to go down with his carrier, but was swept off by the waters and picked up by MICHISHIO. Sixty-nine officers (including Captain Yokoi and XO), and, 1,331 petty officers and men are rescued by destroyers SHIGURE, MICHISHIO, HAMAKAZE, SAMIDARE, AKISHIMO, and HAYASHIMO.
30 June 1944:
Captain Yokoi Toshiyuki is formally released as commanding officer.
10 November 1944:
Removed from the Navy List.
REMARKS & NOTE:
Note 1: This puzzling notation and the following on November 27th 1942 has eluded verification to-date, but comes from a convincing source: Hiyo's microfilm TROM record as translated in WDC # 160677 Group 100, Item A-101 states for November 1942 the following: “On the 4th, she was transferred from Main Unit, Advance Force to Air Force Advance Force. During this month she was subjected to bombing attacks on 4 occasions, sustaining no damages on two of them (11th and 14th) and minor damages on the other two (13th and 27th).” Yet no USAAF or USN air raids on Truk are known in this time frame. Nor do the entries refer to 1943. Since JD-201 microfilm reel original apparently is unreadable, this translation and original meaning at present remains difficult to check. However, as Hiyo was undergoing temporary machinery repairs during this time, it seems most likely the two notations either really refer to damages sustained or inflicted by her aircraft operating out of Buin, Bougainville, or shipboard repair setbacks.
Note 2: Another questionable unconfirmed entry in Hiyo's microfilm TROM as rendered in WDC # 160677 Group 100, Item A-101. Context suggests at Truk, but there is room for doubt. Full quote reads: “April 1943: She remained in Truk during this month, participating in the “I” Operations which was activated on 1st and concluded on 17th. On the 12th, she was subjected to bombing but escaped with minor damages.” Once again, this seems more likely to refer to air group activity connected with I-GO. Or, just possibly, perhaps an Australian action of some kind.
Note 3: An amusing legend spread among U.S. submariners that Trigger's skipper had calmly watched Hiyo preparing to sortie from Tokyo Bay, and lay in wait over days following. Then promptly put her down when she left the safety of the torpedo nets.
Note 4: It will be immediately noticed that in fact, IJN sources appear to confirm the initial U.S. Navy claim that it was George Brown himself that made the dramatic final run and hit on the carrier with a burning plane after his crew had bailed out, only to plunge into the sea after passing the ship. Recent U.S. accounts had tended to discount this claim, but the Hiyo record and witnesses all stress that it was the burning plane that presumably crashed closeby that scored the hit, and not the TBFs safely withdrawing. Final determination of course remains problematical at this late date.
Note 5: To date, this Japanese claim of a submarine torpedo hit on Hiyo has been puzzling, and sometimes speculated to be conflation of the traumatic experiences of the sinking of both Taiho and Shokaku by submarine just the day before. However, IJN official real-time sources always credited a submarine torpedo, and Captain Yokoi's spot report is among the sources. Whatever else it means, the claim of a submarine torpedo is authentic to Hiyo's report. Since no subs were present, what probably happened was a massive induced explosion that doomed salvage efforts and fatally wounded the vessel. The same sources are somewhat unclear whether fire was started by the aerial torpedo hit, or only followed the second explosion. A distinction of some importance. If correct this makes Hiyo one of three Japanese fleet carriers sunk by the same combination of petrol tank vapor and induced explosion within a forty-eight hour period.
Special thanks are due to Gilbert Casse in preparing this TROM, and Bob Hackett, Sander Kingsepp, Bill Somerville and Allyn Nevitt for entries derived from their works.
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