Japanese aircraft carrier Sōryū

Soryu (蒼龍) was an aircraft carrier built for the Imperial Japanese Navy (IJN) during the mid-1930s. A sister ship, JAPANESE AIRCRAFT CARRIER Hiryū, was intended to follow Sōryū, but Hiryū's design was heavily modified and she is often considered to be a separate class entirely. Her aircraft were employed in operations during the Second Sino-Japanese War in the late 1930s and supported the Japanese invasion of French Indochina in mid-1940. During the first month of the Pacific War, she took part in the attack on Pearl Harbor and the Battle of Wake Island. The ship supported the conquest of the Dutch East Indies in January 1942. The following month her aircraft bombed Darwin, Australia and continued to assist in the Dutch East Indies campaign. In April Sōryū aircraft helped sink two British heavy cruisers and a number of merchant ships during the Indian Ocean raid.

After a brief refit, Sōryū and three other fleet carriers of the First Air Fleet (Kido Butai) participated in the Battle of Midway in June 1942. After bombarding American forces on Midway Atoll, the carriers were attacked by aircraft from the island and the carriers USS Enterprise (CV-6), USS Hornet (CV-8), and USS Yorktown (CV-5). Dive bombers from Yorktown crippled Sōryū and set her afire. She could not be salvaged and was ordered to be scuttled to release her attendant destroyers for further operations. She sank with the loss of 711 officers and enlisted men of the 1,103 aboard. The loss of Sōryū and three other IJN carriers at Midway was a crucial strategic defeat for Japan and contributed significantly to the Allies' ultimate victory in the Pacific.

Design
Sōryū was one of two large carriers approved for construction under the 1931–32 Supplementary Program (the other being her near sister ship JAPANESE AIRCRAFT CARRIER Hiryū). As opposed to some earlier Japanese carriers, which were conversions of battlecruiser (JAPANESE AIRCRAFT CARRIER Akagi) or battleship (JAPANESE AIRCRAFT CARRIER Kaga) hulls, Sōryū was designed from the keel up as an aircraft carrier and incorporated lessons learned from the light carrier JAPANESE AIRCRAFT CARRIER Ryūjō.

The ship had a length of 227.5 m overall, a beam of 21.3 m and a draft of 7.6 m. She displaced 16200 t at standard load and 19100 t at normal load. Her crew consisted of 1,100 officers and enlisted men.

Machinery
Sōryū was fitted with four geared steam turbine sets with a total of 152000 shp, each driving one propeller shaft, using steam provided by eight Kampon water-tube boilers. The turbines and boilers were the same as those used in the s. The ship's power and slim, cruiser-type hull with a length-to-beam ratio of 10:1 gave her a speed of 34.5 kn and made her the fastest carrier in the world at the time of her commissioning. Sōryū carried 3710 t of fuel oil which gave her a range of 7750 nmi at 18 kn. The boiler uptakes were trunked to the ship's starboard side amidships and exhausted just below flight deck level through two funnels curved downwards.

Flight Deck & Hangars
The carrier's 216.9 m flight deck was 26 m wide and overhung her superstructure at both ends, supported by pairs of pillars. Sōryū's island was built on a starboard-side extension that protruded beyond the side of the hull so that it did not encroach on the width of the flight deck. Nine transverse arrestor wires were installed on the flight deck and could stop a 6000 kg aircraft. The flight deck was only 12.8 m above the waterline and the ship's designers kept this figure low by reducing the height of the hangars. The upper hangar was 171.3 by and had an approximate height of 4.6 m and the lower was 142.3 by and had an approximate height of 4.3 m. Together they had an approximate total area of 5736 sqm. This caused problems in handling aircraft because the wings of a Nakajima B5N Kate torpedo bomber could neither be spread nor folded in the upper hangar.

Aircraft were transported between the hangars and the flight deck by three elevators, the forward one abreast the island on the centerline and the other two offset to starboard. The forward platform measured 16 x, the middle one 11.5 x, and the rear 11.8 x. They were capable of transferring aircraft weighing up to 5000 kg. Sōryū had an aviation gasoline (avgas) capacity of 570000 l for her designed aircraft capacity of 63, plus nine spares.

Armament
Sōryū's primary AA armament consisted of six twin-gun mounts equipped with 40-caliber 12.7-centimeter Type 89 dual-purpose guns mounted on projecting sponsons, three on either side of the carrier's hull. When firing at surface targets, the guns had a range of 14700 m; they had a maximum ceiling of 9440 m at their maximum elevation of +90 degrees. Their maximum rate of fire was 14 rounds a minute, but their sustained rate of fire was around eight rounds per minute. The ship was equipped with two Type 94 fire-control directors to control the 12.7 cm guns, one for each side of the ship, although the starboard director on the island could control all of the Type 89 guns.

The ship's light anti-aircraft (AA) armament consisted of 14 twin-gun mounts for license-built Hotchkiss 25 mm Type 96 AA guns. Three of these were sited on a platform just below the forward end of the flight deck. The gun was the standard Japanese light AA weapon during World War II, but it suffered from severe design shortcomings that rendered it largely ineffective. According to historian Mark Stille, the weapon had many faults including an inability to "handle high-speed targets because it could not be trained or elevated fast enough by either hand or power, its sights were inadequate for high-speed targets, it possessed excessive vibration and muzzle blast"... These 25 mm guns had an effective range of 1500 - 3000 m, and an effective ceiling of 5500 m at an elevation of +85 degrees. The maximum effective rate of fire was only between 110 and 120 rounds per minute because of the frequent need to change the fifteen-round magazines. The Type 96 guns were controlled by five Type 95 directors, two on each side and one in the bow.

Armor
To save weight, Sōryū was only minimally armored; her waterline belt of 41 mm of Ducol steel only protected the machinery spaces and the magazines. It was backed by an internal anti-splinter bulkhead. The ship's deck was only 25 mm thick over the machinery spaces and 55 mm thick over the magazines and avgas storage tanks.

Construction and service
Following the Japanese ship-naming conventions for aircraft carriers, Sōryū was named "Blue (or Green) Dragon". The ship was laid down at the Kure Naval Arsenal on 20 November 1934, launched on 21 December 1935 and commissioned on 29 January 1937. The ship was assigned to the Second Carrier Division after commissioning and her air group was intended to consist of 18 Mitsubishi A5M ("Claude") monoplane fighters, 27 Aichi D1A2 Type 96 dive bombers, and 12 Yokosuka B4Y ("Jean") Type 96 torpedo bombers, but the A5Ms were in short supply and Nakajima A4N1 biplanes were issued instead. On 25 April 1938, 9 A4Ns, 18 D1A2s, and 9 B4Ys transferred to Nanking to support forces advancing up the Yangtze River. Little is known of their operations there, but one fighter pilot was killed after he shot down a Chinese aircraft. Leaving a few fighters and their pilots behind to serve as the nucleus of a new fighter unit, the air group returned to Sōryū on 10 July. The ship supported operations over Canton in September, but saw no aerial combat. She returned home in December and spent most of the next year and a half training.

In September–October 1940, the ship was based at Hainan Island to support the Japanese invasion of French Indochina. In February 1941, Sōryū moved to Taiwan to reinforce the blockade of Southern China. Two months later, the 2nd Carrier Division was assigned to the First Air Fleet, or "Kido Butai", on 10 April and her air group was detached in mid-July and transferred to Hainan Island to support the occupation of southern Indochina. Sōryū returned to Japan on 7 August and became flagship of the 2nd Division. She was relieved of that role on 22 September as she began a short refit that was completed on 24 October. The ship arrived at Kagoshima two days later and she resumed her former role as flagship of the Division.

Pearl Harbor and subsequent operations
In November 1941 the IJN's Combined Fleet, under Admiral Isoroku Yamamoto, prepared to participate in Japan's initiation of a formal war with the United States by conducting a preemptive strike against the United States Navy's Pacific Fleet base at Pearl Harbor, Hawaii. On 22 November, Sōryū, commanded by Captain Ryusaku Yanagimoto, and the rest of the Kido Butai, under Vice Admiral Chuichi Nagumo and including six fleet carriers from the First, Second, and Fifth Carrier Divisions, assembled in Hitokappu Bay at Etorofu Island. The fleet departed Etorofu on 26 November and followed a course across the north-central Pacific to avoid commercial shipping lanes. At this time the ship embarked 27 Mitsubishi A6M Zero fighters, 18 Aichi D3A "Val" dive bombers, and 18 Nakajima B5N "Kate" torpedo bombers. From a position 230 nmi north of Oahu, Sōryū and the other five carriers, launched two waves of aircraft on the morning of 8 December 1941.

In the first wave, eight B5N "Kate" torpedo bombers were supposed to attack the aircraft carriers that normally berthed on the northwest side of Ford Island, but none were in Pearl Harbor that day; six B5Ns attacked the ships that were present, torpedoing the target ship USS Utah (BB-31), causing her to capsize, and the elderly light cruiser USS Raleigh (CL-7), damaging it. Two of the B5N pilots diverted to their secondary target, ships berthed alongside "1010 Pier" where the fleet flagship was usually moored. That battleship was in drydock and its position was occupied by the light cruiser USS Helena (CL-50) and the minelayer USS Oglala (CM-4). One torpedo passed underneath Oglala and struck Helena in one of her engine rooms; the other rejected these targets and ultimately attacked the battleship USS California (BB-44). The remaining 10 B5Ns were tasked to drop 800 kg armor-piercing bombs on the battleships berthed on the southeast side of Ford Island ("Battleship Row") and may have scored one or two hits on them. The eight A6M Zeros strafed parked aircraft at Marine Corps Air Station Ewa, claiming 27 aircraft destroyed in addition to five aircraft shot down.

The second wave consisted of nine A6M Zeros and 17 D3As. The former attacked Naval Air Station Kaneohe Bay, losing one Zero to American anti-aircraft guns. On the return trip, the Zeros claimed to have shot down two American aircraft while losing two of their own. The D3As attacked various ships in Pearl Harbor, but it is not possible to identify which aircraft attacked which ship. Two of them were shot down during the attack.

While returning to Japan, Vice Admiral Chūichi Nagumo, commander of the First Air Fleet, ordered that Sōryū and Hiryū be detached on 16 December to attack the defenders of Wake Island who had already defeated the first Japanese attack on the island. The two carriers reached the vicinity of the island on 21 December and launched 29 D3As and two B2Ns, escorted by 18 Zeros, to attack ground targets. They encountered no aerial opposition and launched 35 B5Ns and six A6M Zeros the following day. They were intercepted by the two surviving Grumman F4F Wildcat fighters of Marine Fighter Squadron VMF-211. The Wildcats shot down two B5Ns before they were shot down themselves by the Zeros. The garrison surrendered the next day after Japanese troops were landed.

The carriers arrived at Kure on 29 December. They were assigned to the Southern Force on 8 January 1942 and departed four days later for the Dutch East Indies. The ships supported the invasion of the Palau Islands and the Battle of Ambon, attacking Allied positions on the island on 23 January with 54 aircraft. Four days later the carriers detached 18 Zeros and nine D3As to operate from land bases in support of Japanese operations in the Battle of Borneo. On 30 January they destroyed two aircraft on the ground and shot down a Qantas Short Empire flying boat flying to Surabaya to pick up refugees.

Sōryū and Hiryū arrived at Palau on 28 January and waited for the arrival of the carriers Kaga and Akagi. All four carriers departed Palau on 15 February and launched air strikes against Darwin, Australia four days later. Sōryū contributed 18 B5Ns, 18 D3As, and 9 Zeros to the attack while flying Combat Air Patrols (CAP) over the carriers. Her aircraft attacked the ships in port and its facilities, sinking or setting on fire eight ships and causing three others to be beached lest they sink. The Zeros destroyed one Consolidated PBY Catalina seaplane; one D3A was lost. A ship was spotted on the return trip, but all ordnance had been expended so aircraft had to be rearmed and refueled before it could be located and attacked. Several hours later, nine of Sōryū's D3As spotted an American supply ship of, the Don Isidro, hitting it five times, but failed to sink it. Sōryū and the other carriers arrived at Staring Bay on Celebes Island on 21 February to resupply and rest before departing four days later to support the invasion of Java. On 1 March 1942, the ship's D3As damaged the destroyer USS Edsall (DD-219) badly enough for her to be caught and sunk by Japanese cruisers. Later that day they sank the oil tanker USS Pecos (AO-6). The four carriers launched an airstrike of 180 aircraft against Tjilatjep on 5 March, sinking five small ships, damaging an additional nine badly enough that they had to be scuttled, and set the town on fire. Two days later they attacked Christmas Island before returning to Staring Bay on 11 March to resupply and train for the impending Indian Ocean raid. This raid was intended to secure newly conquered Burma, Malaya, and the Dutch East Indies against any Allied attack by destroying base facilities and forces in the eastern Indian Ocean.

Indian Ocean raid
On 26 April, the five carriers of the First Air Fleet departed from Staring Bay; they were spotted by a Catalina about 350 nmi southeast of Ceylon on the morning of 4 April. Nagumo closed to within 120 nmi of Columbo before launching an airstrike the next morning. Sōryū contributed 18 B3Ns and nine Zeros to the force. The pilots of the latter aircraft claimed to have shot down one Fairey Fulmar of 806 Naval Air Squadron, plus seven other fighters while losing one of their own. The D3As and B3Ns inflicted some damage to the port facilities, but a day's warning had allowed the much of the shipping in the harbor to be evacuated. Later that morning the British heavy cruisers HMS Cornwall (56) and HMS Dorsetshire (40) were spotted and Sōryū launched 18 D3As. They were the first to attack and claimed to have made 14 hits on the two ships, sinking both in combination with the dive bombers from the other carriers.

On 9 April, Sōryū contributed 18 B5Ns, escorted by nine Zeros, to the attack on Trincomalee. Her B5Ns were the first to bomb the port while her fighters did not encounter any British fighters. Meanwhile a floatplane from the battleship JAPANESE BATTLESHIP Haruna spotted the small aircraft carrier HMS Hermes (95), escorted by the Australian destroyer HMAS Vampire (D68), and every available D3A was launched to attack the ships. Sōryū contributed 18 dive bombers, but they arrived too late to assist in sinking them and found three other ships further north. They sank the oil tanker British Sergeant and the Norwegian cargo ship Norviken before they were attacked by eight Fulmars of 803 and 806 Naval Air Squadrons. The Royal Navy pilots claimed three D3As shot down for the loss of two Fulmars; the Japanese actually lost four D3As with another five damaged. While this was going on, Akagi narrowly escaped damage when nine British Bristol Blenheim bombers from Ceylon penetrated the CAP and dropped their bombs from 11000 ft. Sōryū had six Zeros aloft, along with 14 more from the other carriers and they accounted for five of the British bombers for the loss of one of Hiryū's Zeros. After launching the D3As that sank Hermes and the other ships, the First Air Fleet reversed course and headed southeast for the Malacca Strait and Japan.

On 19 April, while transiting the Bashi Straits between Taiwan and Luzon en route to Japan, Akagi, Sōryū, and Hiryū were sent in pursuit of the American carriers USS Hornet (CV-8) and USS Enterprise (CV-6), which had launched the Doolittle Raid against Tokyo. They found only empty ocean, however, for the American carriers had immediately departed the area to return to Hawaii. The carriers quickly abandoned the chase and dropped anchor at Hashirajima anchorage on 22 April. Having been engaged in constant operations for four and a half months, the ship, along with the other three carriers of the First and Second Carrier Divisions, was hurriedly refitted and replenished in preparation for the Combined Fleet's next major operation, scheduled to begin one month hence. While at Hashirajima, Sōryū's air group was based ashore at nearby Kasanohara, near Kagoshima, and conducted flight and weapons training with the other First Air Fleet carrier units.

Midway
Concerned by the US carrier strikes in the Marshall Islands, Lae-Salamaua, and the Doolittle raids, Yamamoto was determined to force the US Navy into a showdown to eliminate the American carrier threat. He decided to invade and occupy Midway Atoll, which he was sure would draw out the American carriers to defend it. The Japanese codenamed the Midway invasion Operation MI. Unknown to the Japanese, the US Navy had divined the Japanese plan by breaking its JN-25 code and had prepared an ambush using its three available carriers, positioned northeast of Midway.

On 25 May 1942, Sōryū set out with the Combined Fleet's carrier striking force in the company of Kaga, Akagi, and Hiryū, which constituted the First and Second Carrier Divisions, for the attack on Midway Island. Her aircraft complement consisted of 18 Zeros, 16 D3As, 18 B5Ns, and two prototypes of the new Yokosuka D4Y dive bomber. Also aboard were three A6Ms of the 6th Kokutai intended as the aerial garrison for Midway.

With the fleet positioned 250 nmi northwest of Midway at dawn (04:45 local time) on 4 June 1942, Sōryū's portion of the 108-plane combined air raid was a strike on the airfield on Eastern Island with 18 torpedo bombers escorted by nine Zeros. The air group suffered heavily during the attack, one B5N was shot down en route to the island, another was shot down by AA fire, two were forced to ditch near destroyers on the trip back and four were damaged beyond repair.

The carrier also contributed three Zeros to the total of 11 assigned to the initial CAP over the four carriers. By 07:00 the carrier had six fighters with the CAP which helped to defend the Kido Butai from the first US attackers from Midway Island at 07:10. At this time, Nagumo's carriers were attacked by six US Navy Grumman TBF Avengers from Torpedo Squadron 8 (VT-8) and four United States Army Air Corps (USAAC) Martin B-26 Marauders, all carrying torpedoes. The Avengers went after Hiryū while the Marauders attacked Akagi. The 30 CAP Zeroes in the air at this time, including the six from Sōryū, immediately attacked the American airplanes, shooting down five of the Avengers and two of the B-26s. The surviving aircraft dropped their torpedoes, but all missed. Sōryū launched three more Zeros to reinforce the CAP at 07:10.

At 07:15 Admiral Nagumo ordered the B5Ns on Kaga and Akagi rearmed with bombs for another attack on Midway itself. This process was limited by the number of ordnance carts used to handle the bombs and torpedoes and the limited number of ordnance elevators. This meant that the torpedoes could not be struck below until after all the bombs were moved up from their magazine, assembled and mounted on the aircraft. This process normally took about an hour and a half; more time would be required to bring the aircraft up to the flight deck, warm up and launch the strike group. Around 07:40 he reversed his order when he received a message from one of his scout aircraft that American warships had been spotted. Depleted of ammunition, the first six of Sōryū's CAP Zeroes landed aboard the carrier at 07:30.

At 07:55, the next American strike from Midway arrived in the form of 16 Marine Douglas SBD Dauntless dive bombers of Marine Scout Bomber Squadron (VMSB-241) under Major Lofton R. Henderson. Sōryū's three CAP fighters were among the nine still aloft that attacked Henderson's planes, shooting down six of them as they executed a fruitless glide bombing attack on Hiryū. At roughly the same time, the Japanese carriers were attacked by 12 USAAC Boeing B-17 Flying Fortresses, bombing from 20000 ft. The high altitude of the B-17s gave the Japanese captains enough time to anticipate where the bombs would land and successfully maneuver their ships out of the impact area. Four B-17s attacked Sōryū, but missed with all their bombs.

The CAP defeated the next American air strike from Midway, 11 Vought SB2U Vindicator dive bombers from VMSB-241, which attacked the battleship Haruna starting around 08:30. Three of the Vindicators were shot down, and Haruna escaped damage. Although all the American air strikes had thus far caused negligible damage, they kept the Japanese carrier forces off-balance as Nagumo endeavored to prepare a response to news, received at 08:20, of the sighting of American carrier forces to his northeast. Around 08:30 Sōryū launched one of her D4Ys on a mission to confirm the location of the American carriers.

Sōryū began recovering her Midway strike force at around 08:40 and finished shortly by 09:10. The landed aircraft were quickly struck below, while the carriers' crews began preparations to spot aircraft for the strike against the American carrier forces. The preparations, however, were interrupted at 09:18 when the first American carrier aircraft to attack were sighted. These consisted of 15 Douglas TBD Devastator torpedo bombers of VT-8, led by Lieutenant Commander John C. Waldron from the Hornet. The three airborne CAP Zeroes were landing aboard at 09:30 when the Americans unsuccessfully attempted a torpedo attack on Soryū, but three of the morning's escort fighters were still aloft and joined the 18 CAP fighters in destroying Waldron's planes. All of the American planes were shot down, leaving one surviving aviator treading water.

Shortly afterwards, 14 Devastators from Torpedo Squadron 6 (VT-6) from the Enterprise, led by Lieutenant Commander Eugene E. Lindsey, attacked. Lindsey's aircraft tried to sandwich Kaga, but the CAP, reinforced by three additional Zeros launched by Sōryū at 09:45, shot down all but four of the Devastators, and Kaga dodged the torpedoes. Sōryū launched another trio of CAP Zeros at 10:00 and another three at 10:15 after Torpedo Squadron 3 (VT-3) from Yorktown was spotted. One of her Zeros was shot down by a Wildcat escorting VT-3.

While VT-3 was still attacking Hiryū, American dive bombers arrived over the Japanese carriers almost undetected and began their dives. It was at this time, around 10:20, that in the words of Jonathan Parshall and Anthony Tully, the "Japanese air defenses would finally and catastrophically fail." At 10:25, Sōryū was attacked by thirteen Dauntlesses from Bombing Squadron 2 (VB-2) from the USS Yorktown (CV-5). The carrier received three direct hits from 454 kg (1000 lb) bombs: one penetrated to the lower hangar deck amidships, and the other two exploded in the upper hangar deck fore and aft. The hangars contained armed and fueled aircraft preparing for the upcoming strike, resulting in secondary explosions and rupturing the steam pipes in the boiler rooms. Within a very short time the fires on the ship were out of control. At 10:40 AM she stopped and her crew was ordered to abandon ship five minutes later. The destroyers JAPANESE DESTROYER Isokaze and JAPANESE DESTROYER Hamakaze rescued the survivors. Sōryū was still afloat and showed no signs of beginning to sink by early evening, so Isokaze was ordered to scuttle her with torpedoes to allow the destroyers to be used for possible operations that night. The destroyer reported at 19:15 that Sōryū had sunk at position 30.63333°N, -179.21667°W. Losses were 711 crew of her nominal complement of 1,103, including Captain Yanagimoto, who chose to remain on board. This was the highest mortality percentage of all the Japanese carriers lost at Midway, due largely to the devastation in both hangar decks.

The loss of Sōryū and the three other IJN carriers at Midway, comprising two thirds of Japan's total number of fleet carriers and the experienced core of the First Air Fleet, was a crucial strategic defeat for Japan and contributed significantly to Japan's ultimate defeat in the war. In an effort to conceal the defeat, the ship was not immediately removed from the Navy's registry of ships, awaiting a "suitable opportunity" before finally being struck from the registry on 10 August 1942.