was an aircraft carrier built for the Imperial Japanese Navy (IJN) during the mid-1930s. A sister ship, , was intended to follow Sōryū, but Hiryūs design was heavily modified and she is often considered to be a separate class. Sōryūs 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 months of the Pacific War, she took part in the attack on Pearl Harbor, the Battle of Wake Island, and supported the conquest of the Dutch East Indies. In February 1942, her aircraft bombed Darwin, Australia, and she continued on to assist in the Dutch East Indies campaign. In April, Sōryū aircraft helped sink two British heavy cruisers and several merchant ships during the Indian Ocean raid.

After a brief refit, Sōryū and three other carriers of the 1st Air Fleet (Kidō 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 , , and . Dive bombers from Yorktown crippled Sōryū and set her afire. Japanese destroyers rescued the survivors but the ship could not be salvaged and was ordered to be scuttled so as to allow her attendant destroyers to be released 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 and description Sōryū was one of two large carriers approved for construction under the Imperial Japanese Navy's 1931–32 Supplementary Program (the other being her near-sister Hiryū). In contrast to some earlier Japanese carriers, such as and , which were conversions of battlecruiser and battleship hulls respectively, Sōryū was designed from the keel up as an aircraft carrier and incorporated lessons learned from the light carrier .Chesneau, p. 165

The ship had a length of overall, a beam of and a draught of . She displaced at standard load and at normal load. Her crew consisted of 1,100 officers and ratings.Jentschura, Jung & Mickel, p. 47

Machinery

Sōryū was fitted with four geared steam turbine sets with a total of , each driving one propeller shaft using steam provided by eight 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 Brown 1977, pp. 18–19 and made her the fastest carrier in the world at the time of her commissioning.Parshall & Tully, p. 9 Sōryū carried of fuel oil which gave her a range of at . The boiler uptakes were trunked together to the ship's starboard side amidships and exhausted just below flight deck level through two funnels curved downwards.Peattie, p. 239

Flight deck and hangars The carrier's flight deck was wide and overhung her superstructure at both ends, supported by pairs of pillars. Sōryūs 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 aircraft. The flight deck was only above the waterline and the ship's designers kept this distance low by reducing the height of the hangars.Brown 1977, p. 18 The upper hangar was and had an approximate height of ; the lower was and had an approximate height of . Together they had an approximate total area of . 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.Chesneau, p. 166 The forward platform measured , the middle one , and the rear . They were capable of transferring aircraft weighing up to . Sōryū had an aviation gasoline capacity of for her planned aircraft capacity of sixty-three plus nine spares.

Armament Sōryūs primary anti-aircraft (AA) armament consisted of six twin-gun mounts equipped with 50-caliber 12.7-centimeter Type 89 dual-purpose guns mounted on projecting sponsons, three on either side of the carrier's hull. The guns had a range of , and a ceiling of at an elevation of +90 degrees. Their maximum rate of fire was fourteen rounds a minute, but their sustained rate of fire was around eight rounds per minute.Campbell, pp. 192–193 The ship was equipped with two Type 94 fire-control directors to control the guns, one for each side of the ship,Parshall & Tully, p. 143 although the starboard director on the island could control all of the Type 89 guns.Brown 1977, p. 19

The ship's light AA armament consisted of fourteen twin-gun mounts for license-built Hotchkiss 25 mm (1 in) 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".Stille 2007, p. 51 These guns had an effective range of , and a ceiling of at an elevation of +85 degrees. The effective rate of fire was only between 110 and 120 rounds per minute because of the frequent need to change the 15-round magazines.Campbell, p. 200 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 minimally armored; her waterline belt of of Ducol steel only protected the machinery spaces and the magazines. Comparable figures for Hiryū were over the machinery spaces and the aviation gasoline storage tanks increasing to over the magazines. Sōryūs waterline belt was backed by an internal anti-splinter bulkhead. The ship's deck was only 25 mm thick over the machinery spaces and thick over the magazines and aviation gasoline storage tanks.

Construction and service

Following the Japanese ship-naming conventions for aircraft carriers, Sōryū was named "Blue (or Green) Dragon".Silverstone, p. 337 The ship was laid down at the Kure Naval Arsenal on 20 November 1934, launched on 23 December 1935 and commissioned on 29 December 1937.Sturton, p. 181 She was assigned to the Second Carrier Division after commissioning. Her air group was initially intended to consist of eighteen Mitsubishi A5M ("Claude") monoplane fighters, twenty-seven Aichi D1A2 ("Susie") Type 96 dive bombers, and twelve 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, nine A4Ns, eighteen D1A2s, and nine B4Ys transferred to Nanjing to support forces advancing up the Yangtze River. The air group advanced with the successful Japanese offensive, despite the defense by the Chinese Air Force and the Soviet Volunteer Group; it was transferred to Wuhu in early June and then to Anqing. Little is known of its operations there, but its primary role during this time was air defense. One fighter pilot of the group 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 her aircraft saw no aerial combat. She returned home in December and spent most of the next year and a half training.Hata, Izawa & Shores, pp. 150–151; Hooton, p. 15

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.Hata, Izawa & Shores, p. 151 Two months later, the 2nd Carrier Division was assigned to the First Air Fleet, or Kido Butai, on 10 April.Tully Sōryūs 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 war with the United States by conducting a preemptive strike against the US 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, 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.Polmar & Genda, p. 162 At this time Sōryū embarked 21 Mitsubishi A6M Zero fighters, 18 Aichi D3A "Val" dive bombers, and 18 Nakajima B5N torpedo bombers. From a position north of Oahu, Sōryū and the other five carriers launched two waves of aircraft on the morning of 8 December 1941 (Japan time).Brown 2009, pp. 116–117Japan Standard Time is 19 hours ahead of Hawaiian Standard Time, so in Japan, the attack on Pearl Harbor happened on 8 December.

In the first wave, eight of Sōryūs B5Ns 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 , causing her to capsize, and the elderly light cruiser , damaging her. 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 her position was occupied by the light cruiser and the minelayer . One torpedo passed underneath Oglala and struck Helena in one of her engine rooms; the other pilot rejected these targets and attacked the battleship . Her other ten B5Ns were tasked to drop 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.Zimm, pp. 159–60, 164, 168 Her eight A6M Zeros strafed parked aircraft at Marine Corps Air Station Ewa, claiming twenty-seven aircraft destroyed in addition to five aircraft shot down.

Sōryūs second wave consisted of nine A6M Zeros and seventeen D3As.Polmar & Genda, p. 166 The former attacked Naval Air Station Kaneohe Bay, losing one Zero to American anti-aircraft guns. On the return trip, the Zero pilots 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.Brown 2009, pp. 118–119 Two of them were shot down during the attack.Polmar & Genda, p. 173