Japanese aircraft carrier Jun'yō

Jun'yō (隼鷹) was a Hiyō-class aircraft carrier of the Imperial Japanese Navy. She was laid down at Nagasaki as the passenger liner Kashiwara Maru, but was purchased by the Japanese Navy in 1941 and converted to an aircraft carrier. Completed in May 1942, the ship participated in the invasion of the Aleutian Islands the following month and in several battles during the Guadalcanal Campaign in late 1942. Her aircraft were disembarked several times and used from land bases in a number of battles in the South West Pacific. Jun'yō was torpedoed in November 1943 and spent three months under repair. She was damaged by several bombs during the Battle of the Philippine Sea in mid-1944, but was quickly repaired. Lacking aircraft, she was used as a transport in late 1944 and was torpedoed in December. Jun'yō was under repair until March 1945 when the repairs were deemed uneconomical. She was then effectively hulked for the rest of the war. The ship was deemed not worth the cost to repair by the Americans after the surrender of Japan in September and she was broken up in 1946–47.

Design and description
The ship was ordered as the fast luxury passenger liner Kashiwara Maru by Nippon Yusen Kaisha (Japan Mail Steamship company) in late 1938. In exchange for a 60% subsidy of her building costs by the Navy Ministry, she was designed to be converted to an aircraft carrier.

Jun'yō had a length of 219.32 m overall. She had a beam of 26.7 m and a draft of 8.15 m. She displaced 24150 t at standard load. Her crew ranged from 1,187 to 1,224 officers and men.

The ship was fitted with two Mitsubishi-Curtis geared steam turbine sets with a total of 56250 shp, each driving a 5.5 m propeller. Steam was provided by six Mitsubishi three-drum water-tube boilers at a pressure of 40 kg/cm2 at a temperature of 420 °C. Her machinery, designed for merchant service, was over four times heavier that that of the JAPANESE AIRCRAFT CARRIER Hiryū. Jun'yō had a designed speed of 25.5 kn, but reached 26 kn during her sea trials. The ship carried 4100 t of fuel oil which gave her a range of 12251 nmi at 18 kn.

Flight deck arrangements
Jun'yō's flight deck was 210.3 m long and had a maximum width of 27.3 m. A large island was fitted on the starboard side that was integrated with, for the first time in a Japanese carrier, the ship's funnel. This was angled 26° outwards to help keep its exhaust from interfering with flight operations. The ship was designed with two superimposed hangars, each approximately 153 m long, 15 m wide and 5 m high. Each hangar could be subdivided by four fire curtains and they were fitted with fire fighting foam dispensers on each side. The hangars were served by two square aircraft elevators with rounded corners, 14.03 m on each side. The elevators had a maximum capacity of 5000 kg and took 15 seconds to go from the lower hangar to the flight deck. Jun'yō was fitted with electrically operated Kure type model 4 arresting gear with nine cables. She also mounted two Type 3 crash barricades. No aircraft catapult was fitted. The ship mounted a crane on the port side of the flight deck, just aft of the rear elevator. When collapsed, it was flush with the flight deck.

The ship's air group was originally intended to consist of 12 Mitsubishi A5M 'Claude' fighters, plus four in storage, 18 Aichi D3A 'Val' dive bombers, plus two in reserve, and 18 Nakajima B5N 'Kate' torpedo bombers. This was revised to substitute a dozen Mitsubishi A6M Zero fighters, and three in storage for the A5Ms by the time the ship commissioned in 1942. As a result of the lessons learned from the Battle of Midway in June, the ship's fighter complement was strengthened to 21 Zeros, and the other aircraft reduced to 12 D3As and 9 B5Ns. By the end of the year, six more Zeros replaced an equal number of D3As. Although it was possible to fit all these aircraft into the hangars, eight or nine were usually stored on the flight deck to reduce cramping below decks.

Armor, armament and sensors
As a conversion from an ocean liner, it was not possible to add much armor, although the ship had a double hull. Two plates of Ducol steel, each 25 mm thick, protected the sides of the ship's machinery spaces. The ship's aviation gasoline tanks and magazines were protected by one layer of Ducol steel. In addition, her machinery spaces were further subdivided by transverse and longitudinal bulkheads to limit any flooding.

The ship's primary armament consisted of a dozen 40-caliber 12.7 cm Type 89 anti-aircraft (AA) guns in twin mounts on sponsons along the sides of the hull. Jun'yō was also initially equipped with eight triple 25 mm Type 96 light AA guns, also in sponsons along the sides of the hull. In mid-1943, four more triple mounts were added and another four triple mounts in late 1943–early 1944. Two of these last four mounts were mounted on the stern and the others were placed in front of and behind the island. A dozen single mounts were also added, some of which were portable and could be mounted on tie-down points on the flight deck. After the Battle of the Philippine Sea in June 1944, the ship's anti-aircraft armament was reinforced with three more triple mounts, two twin mounts and 18 single mounts for the 25 mm Type 96 gun. These guns were supplemented by six 28-round AA rocket launchers. In October 1944, Jun'yō had a total of 91 25 mm barrels; 57 in 19 triple mounts, four in two twin mounts, and 30 single mounts.

Two Type 94 high-angle fire-control directors, one on each side of the ship, were fitted to control the Type 89 guns. Each director mounted a 4.5 m rangefinder. When Jun'yō first commissioned only the rangefinders were fitted and the directors were added later. Four Type 95 directors controlled the 25 mm guns and another pair were added in early 1943. Early warning was provided by two Type 2, Mark 2, Model 1 air search radars. The first of these was mounted on the top of the island in July 1942, shortly after she was completed, and the other was added later in the year. This latter system was fitted on the port side of the hull, outboard of the rear elevator. A smaller Type 3, Mark 1, Model 3 air search radar was added in 1944.

Career
Jun'yō's keel was laid down by Mitsubishi Heavy Industries Shipyard, Nagasaki, on 20 March 1939 with the name of Kashiwara Maru. The ship was purchased on 10 February 1941 by the Navy Ministry and she was temporarily referred to as No. 1001 Ship (Dai 1001 bankan) to keep her conversion secret. She was launched on 26 June 1941 and commissioned on 3 May 1942.

Upon commissioning, the ship was assigned to the Fourth Carrier Division of the 1st Air Fleet, together with JAPANESE AIRCRAFT CARRIER Ryūjō, under the command of Rear Admiral Kakuji Kakuta. She was tasked to support Operation AL, an attack planned to seize several Aleutian Islands to provide advance warning in case of an American attack from the Aleutians down the Kurile Islands while the main body of the American fleet was occupied defending Midway. Jun'yō carried 18 A6M2 Zeros and 18 D3As for this operation. At dawn on 3 June, she launched nine Zeros and a dozen D3As to attack Dutch Harbor on Unalaska Island. They had to turn back due to bad weather although one PBY Catalina reconnaissance aircraft was shot down by a Zero. A second airstrike was launched later in the day to attack a group of destroyers discovered by aircraft from the first attack, but they failed to find the targets. Another airstrike was launched on the following day by the two carriers that consisted of 15 Zeros, 11 D3As, and 6 B5Ns and successfully bombed Dutch Harbor. As the aircraft from Jun'yō were regrouping after the attack, they were attacked by eight Curtiss P-40 fighters that shot down two Zeros and a pair of D3As while losing two of their own. One more D3A got lost and failed to make it back to the carrier. Shortly after the aircraft were launched, the Americans attacked the carriers, but failed to inflict any damage. A Martin B-26 Marauder bomber and a PBY were shot down by Zeros, and a Boeing B-17 Flying Fortress bomber was shot down by flak during the attack.

Jun'yō had initially been designated as an auxiliary aircraft carrier (Toketsetsu kokubokan), but following the loss of four Japanese fleet carriers in the Battle of Midway, she was redesignated as a regular carrier (Kokubokan) in July. Captain Okada Tametsugu assumed command on 20 July 1942. Upon arrival at Truk on 9 October, together with her sister JAPANESE AIRCRAFT CARRIER Hiyō, the ship was assigned to the Second Carrier Division to begin operations against American forces in the Guadalcanal area as part of the 3rd Fleet. On 15 October, the two carriers reached the vicinity of Malaita Island in the Solomon Islands and their aircraft discovered a resupply convoy for Guadalcanal that was escorted by the destroyer USS Meredith (DD-434). The A6M Zeros and D3As from the sisters attacked and sank the destroyer. The next day, they found the small seaplane tender, USS McFarland (DD-237), in Lunga Roads offloading avgas into barges. Nine D3As attacked, blowing the ship's stern off and destroying the barge. McFarland was not sunk, but required months of repairs. The two carriers were intended to play a prominent role in the Japanese effort to retake Guadalcanal Island and were assigned to the Advance Force for this operation. Their aircraft were supposed to provide air cover after the Japanese night attack that retook Henderson Field and then they were to be flown ashore.

In late October 1942, during the Guadalcanal Campaign, Jun'yō took part in the Battle of the Santa Cruz Islands. At this time, her air group consisted of 18 Zeros, 18 D3As and nine B5Ns. On 05:00 on 26 October 1942, she had launched fourteen Zeros and a few D3As to land at Henderson Field on Guadalcanal, which had been falsely reported by the Imperial Japanese Army as in their hands, but they were greeted by Marine Grumman F4F Wildcats and all were shot down. At 09:30, Jun'yō launched another air strike that attacked the carrier USS Enterprise (CV-6), the battleship USS South Dakota (BB-57) and the light cruiser USS San Juan (CL-54), scoring hits on the latter two, but with little substantial damage. Three D3As and a B5N were shot down by returning Douglas SBD Dauntless dive bombers. Most of the surviving Japanese aircraft were forced to land on the undamaged Jun'yō and Rear Admiral Kakuta launched another air strike at 1415, using six B5Ns from JAPANESE AIRCRAFT CARRIER Shōkaku and nine D3As from both carriers. Shortly afterwards, more aircraft were launched to attack the American ships, including six B5Ns, six D3As, escorted by six Zeros. All of these aircraft attacked the carrier USS Hornet (CV-8), which had been badly damaged by the attacks earlier in the day. American damage control measures had been partially successful, but one torpedo hit by a B5N from Shōkaku increased her list from 7.5° to 14.5° and near-misses by the dive bombers started enough seams in her plating that her list increased to 18°. The Americans finally ordered the ship abandoned and the last wave of dive bombers hit Hornet twice more, but inflicted little further damage.

In mid-November 1942, Jun'yō was tasked to provide air cover for the convoy bringing reinforcements for the Japanese forces on Guadalcanal during the three-day-long Naval Battle of Guadalcanal. The ship had 27 A6M3 Zeros, 12 D3A2s and nine B5N2s for this task. Six of her Zeros were overhead when the convoy was discovered by two SBDs from Enterprise and shot down one dive bomber after it had made its spot report. They were unable to protect the convoy against further attacks by aircraft based at Henderson Field; seven transports were sunk and the remaining four transports were damaged before the end of the day. That afternoon, Enterprise had been discovered by a searching B5N and Junyo launched an air strike with her remaining aircraft, but they failed to locate the American carrier. In December 1942 – January 1943, the carrier covered several convoys that brought reinforcements to Wewak, New Guinea and her air group was based there for several days to protect the forces there before returning to Truk on 20 January. The ship then covered the evacuation of forces from Guadalcanal through early February.

Jun'yō briefly returned to Japan in February before she sailed for Truk on 22 March together with Hiyō. Her air group was detached to Rabaul on 2 April to participate in Operation I-Go, a land-based aerial offensive against Allied bases in the Solomon Islands and New Guinea. The carrier was lightly damaged from bomb splinters on 12 April from an American air attack. She returned to Japan on 22 May and departed Yokosuka on 10 June with Hiyō, but the latter ship was torpedoed that evening. Hiyō's aircraft were split between JAPANESE AIRCRAFT CARRIER Ryūhō and Jun'yō and they reached Truk a few days later. The ship's air group was deployed to Buin, Papua New Guinea on 2 July in response the American invasion of Rendova Island on 30 June. Leaving her aircraft behind, the carrier returned to Japan in late July.

Jun'yō ferried aircraft to Singapore in mid-August and troops and equipment to the Caroline Islands the following month. On 5 November 1943 off Bungo Suido, en route from Truk to Kure, Jun'yō was hit by a torpedo from the submarine USS Halibut (SS-232). Four men were killed, but the damage was light, other than the disabled rudder. The ship was under repair and refit until 29 February 1944 at Kure. Meanwhile, her air group had been reconstituted at Singapore on 1 November with 24 Zeros, 18 D3As and 9 B5Ns. The aircraft transferred to Truk on 1 December and then to Kavieng at the end of December before reaching Rabaul on 25 January 1944; the survivors were back at Truk on 20 February and the air group was disbanded.

In the meantime, the Japanese Navy had restructured its carrier air groups so that one air group was assigned to one carrier division and Air Group 652 was assigned to the 2nd Carrier Division with Hiyō, Jun'yō and Ryūhō on 1 March. The air group was last in priority to be rebuilt and only had 30 Model 21 Zeros, 13 Model 52 Zeros and four D3As on hand on 1 April of its authorized 81 fighters, 36 dive bombers and 27 torpedo bombers. The ship conducted training for her aircraft in the Inland Sea until 11 May when she sailed for Tawi-Tawi in the Philippines. The new base was closer to the oil wells in Borneo on which the Navy relied and also to the Palau and western Caroline Islands where the Japanese expected the next American attack. However, the location lacked an airfield on which to train the green pilots and American submarines were very active in the vicinity which restricted the ships to the anchorage.

Battle of the Philippine Sea
The Japanese fleet was en route to Guimares Island in the central Philippines on 13 June, where they intended to practice carrier operations in an area better protected from submarines, when Vice Admiral Jisaburō Ozawa learned of the American attack on the Mariana Islands the previous day. Upon reaching Guimares, the fleet refuelled and sortied into the Philippine Sea where they spotted Task Force 58 on 18 June. The Americans failed to locate Ozawa's ships that day and the Japanese turned south to maintain a constant distance between them and the American carriers as Ozawa had decided on launching his air strikes early the following morning. At this time, Air Group 652 consisted 81 Zeros, 27 D3As, 9 Yokosuka D4Y "Judy" dive bombers and 18 Nakajima B6N "Jill" torpedo bombers, roughly evenly divided among the three ships. The three carriers began launching their first air strike of 26 bomb-carrying A6M2 Zeros, 16 A6M5 Zeros to escort the other aircraft and seven B6Ns at about 09:30. Most of these aircraft were misdirected and failed to find any American ships, although a dozen persisted in their search and found one of the American task groups. Five bomb-carrying Zeros, a B6N and an escort Zero were shot down by the defending fighters and no damage was inflicted on any American ship.

A second air strike of 27 D3As, nine D4Ys, two B6Ns and 26 escorting Zeros was launched around 11:00, accompanied by at least 18 A6Ms and B6Ns from Shōkaku and JAPANESE AIRCRAFT CARRIER Zuikaku. They had also been given an erroneous spot report and could not find any American ships. The 652nd aircraft headed for airfield at Rota and Guam to refuel while those from the other two carriers headed back to them. Six D4Ys and two Zeros bound for Rota spotted the carriers USS Wasp (CV-18) and USS Bunker Hill (CV-17) en route and failed to inflict any damage on the American ships while losing five D4Ys to anti-aircraft fire. Radar had spotted those aircraft headed for Guam and they were intercepted by 41 Grumman F6F Hellcats. Only one A6M5, one D4Y and seven D3As of the 49 Japanese aircraft survived the encounter and landed. By the end of the day, Air Group 652 had been reduced to only 38 Zeros, evenly split between bomb-carrying A6M2s and escort A6M5s, and eight B6Ns.

At dusk, the Japanese turned away to the northwest to regroup and to refuel and the Americans turned west to close the distance. They discovered the retiring Japanese fleet during the afternoon of the following day and Vice Admiral Marc Mitscher ordered an air strike launched. They discovered the ships of the Second Carrier Division and hit Jun'yō with two bombs near her island. The ship was not badly damaged, but the damage did stop flight operations. Air Group 652 claimed two Grumman F6F Hellcat fighters and nine Grumman TBF Avenger torpedo bombers shot down, but lost 11 aircraft, plus another three that had to ditch. By the end of the battle, the air group only consisted of 11 A6M5s, 5 A6M2s and 1 B6N and it was disbanded on 10 July. Most of its remaining personnel were assigned to Air Group 653.

After repairs at Kure, she remained in the Inland Sea without aircraft until 27 October when she was tasked to transport material to Borneo. On 3 November, while en route, she was attacked by the submarine USS Pintado (SS-387) near Makung, but her escorting destroyer, JAPANESE DESTROYER Akikaze, deliberately sacrificed herself by intercepting the torpedoes and sank with no survivors. On her return voyage, the ship was unsuccessfully attacked by the submarines USS Barb (SS-220) and USS Jallao (SS-368). On 25 November, she sailed for Manila via Makung to rendezvous with the battleship JAPANESE BATTLESHIP Haruna and the destroyers Suzutsuki, Fuyutsuki, and Maki. Having loaded 200 survivors of the battleship JAPANESE BATTLESHIP Musashi, Jun'yō was attacked by the submarines USS Sea Devil (SS-400), USS Plaice (SS-390) and USS Redfish (SS-395) early in the morning of 9 December 1944. She was hit by three torpedoes that flooded several compartments and killed 19 men. These give her a 10°–12° list to starboard, but she was able to proceed on one engine. She reached Sasebo the following day and began repairs on 18 December.

The repairs were abandoned in March 1945 for lack of materials and the ship was moved from the dock to Ebisu Bay, Sasebo on 1 April. Efforts to camouflage the ship began on 23 April and she was reclassified as a guard ship on 20 June. Jun'yō's armament was ordered removed on 5 August and the ship was surrendered to the Allies on 2 September. An American technical team evaluated the ship's condition on 8 October and deemed her a constructive total loss. Jun'yō was stricken from the Navy List on 30 November and scrapped between 1 June 1946 and 1 August 1947 by the Sasebo Ship Company.

Jun'yō's ship bell
Jun'yō's ship's bell was recovered by the U.S. Navy near Saipan, having been separated from the ship by a bomb impact. The bell was given to Fordham University by Admiral Chester W. Nimitz in 1944, "As a Memorial to Our Dear Young Dead of World War II," according to the associated memorial plaque. It was blessed by Cardinal Spellman, the Roman Catholic Archdiocese of New York, and "[w]as first rung at Fordham by the President of the United States, the Honorable Harry S. Truman on 11 May 1946, the Charter Centenary of the University." it is still there.