Sōryū

The Vessel

The Imperial Japanese Navy aircraft carrier Sōryū ("Blue Dragon") was the lead ship of her class, a pair of medium fleet carriers built to a specific Japanese design philosophy: fast, light, and carrying larger aircraft complements than their smaller displacement would suggest. She was commissioned at the Kure Naval Arsenal on 29 December 1937, 227 metres long, 15,900 tons, capable of 34.5 knots, and carried 63 aircraft (21 fighters, 18 dive bombers, 21 torpedo bombers, 3 reserves). She was the first Japanese carrier designed from the keel up as an aircraft carrier; her hull form had been optimised for aircraft operations rather than converted from a larger warship type.

Her sister Hiryū, commissioned in 1939, was the same design but with a port-side island rather than the starboard-side arrangement typical of all other carriers. The two ships operated as a close pair from 1939 onward. Their design emphasis on speed and lightness gave them approximately 35 per cent more operational aircraft per thousand tons than the contemporary Akagi and Kaga, a significant operational advantage for Japanese carrier doctrine.

Her service record from 1939 through May 1942 was the most operationally successful of any Japanese fleet carrier. She had led the opening attack on Pearl Harbor as part of the First Air Fleet; had participated in every major Kidō Butai operation; and by June 1942 had sunk, directly or indirectly through her aircraft, more Allied ships than any carrier afloat.

The Voyage

On 4 June 1942 Sōryū was operating in the starboard column of the Kidō Butai carrier formation, in company with her sister Hiryū. Her combat operations through the morning had followed a pattern similar to Akagi and Kaga: a dawn strike on Midway; re-arming for a second strike against the American carriers; attacks by uncoordinated American torpedo bomber squadrons through 09:20-10:00 that had been repulsed with heavy American losses and no Japanese damage.

At 10:25 on 4 June 1942, three minutes after Akagi and Kaga were struck, Sōryū was attacked by the dive bombers of USS Yorktown's VB-3 squadron under the command of Lieutenant-Commander Maxwell F. Leslie. Leslie had inadvertently lost his own bomb during the approach (it had fallen clear when he tested his electrical bomb-release circuit) but continued to lead his squadron into the attack as a dive director. Leslie's 17 Douglas SBD Dauntless dive bombers were aligned specifically on Sōryū because her position in the starboard column had placed her nearest to the arriving American formation.

The Leslie dive-bombing attack on Sōryū was the most concentrated of the three Midway carrier attacks of 10:22-10:25. Leslie's dive bombers scored three direct hits within approximately 90 seconds.

The Disaster

The three American 1,000-pound bombs struck Sōryū in quick succession between 10:25 and 10:26 on 4 June 1942. The first bomb struck her forward flight deck at Frame 25; the second struck her mid-flight deck at Frame 50; the third struck her stern just aft of the island. All three bombs penetrated the flight deck before detonating on the hangar deck below. The pattern of hits was extraordinarily good: the three strikes were distributed along her full length, ensuring that no single damage-control party could contain the resulting fires.

Sōryū's hangar deck was filled at the moment of the attack with re-armed Nakajima B5N Kate torpedo bombers, their Type 91 aerial torpedoes (each carrying 204 kilograms of TNT) lying in their bays, and their aircraft fuelled for the second strike. The three bombs, landing among this arrangement, ignited a chain reaction of torpedo and bomb detonations that compressed approximately ten individual aircraft explosions into a six-second sequence. Contemporary American combat photographs of Sōryū from 10:26 show a single continuous pillar of flame rising approximately 1,000 metres above her flight deck.

Captain Ryūsaku Yanagimoto, the senior officer aboard, was killed on the bridge within 45 seconds of the first bomb strike. Commander Hisashi Ohara, her executive officer, assumed command. By 10:35, nine minutes after the first strike, Sōryū was on fire from end to end and was unable to manoeuvre. Ohara ordered abandon-ship at 10:40, unusually early in the emergency response timeline for a Japanese carrier; the decision was subsequently credited with saving the lives of approximately 392 of her 1,103 crew.

Sōryū continued to burn through the afternoon. At 19:12 on 4 June 1942 the submarine USS Nautilus (SS-168), operating in the area by coincidence, fired three torpedoes at the burning hulk. One torpedo struck her port side amidships; the hit was probably incidental to her eventual sinking, as she was already in extremis from her internal fires. Sōryū capsized and sank at 19:13 at approximately 30°38′N 179°13′W in approximately 5,400 metres of water.

The Legacy

The loss of Sōryū was, among the four Japanese carriers lost at Midway, the most significant from the perspective of Japanese naval aviation doctrine. Her air group had contained the highest concentration of pre-war trained naval aviators of any Japanese carrier; her Aichi D3A Val dive-bomber squadron under Lieutenant-Commander Takashi Hashiguchi had been the most experienced in the Imperial Japanese Navy. The loss of approximately 120 experienced aircrew aboard Sōryū in the chain of explosions and subsequent fires removed from Japanese service a significant fraction of the carrier aviation expertise Japan had accumulated in the 1930s China campaigns.

Sōryū's sister Hiryū launched a counter-strike against the American carriers later on 4 June 1942 that damaged USS Yorktown and began the subsequent sequence that would ultimately destroy Hiryū herself. The strategic consequence of the four-carrier loss was that the Imperial Japanese Navy's fleet carrier strength was reduced from six fleet carriers to two (Shōkaku, Zuikaku) in a single afternoon, with the two surviving fleet carriers both damaged from the Coral Sea engagement of a month earlier.

The wreck of Sōryū was located on 19 October 2019 by the Petrel expedition at a depth of 5,400 metres, approximately 3 kilometres south-southeast of Kaga's wreck site. Sōryū lies upright on the Pacific abyssal plain, her hull intact but her flight deck showing the bomb-strike damage. The Petrel imagery revealed that her starboard aft elevator was in the raised position at the moment of her sinking, and that her flight deck showed the specific three-bomb pattern described by Leslie's squadron after-action report. The agreement between the 1942 verbal reports and the 2019 visual survey has provided unusually strong forensic confirmation of the Leslie squadron's account.

The 711 dead of Sōryū are commemorated at the Yasukuni Shrine. Her name has not been carried by any subsequent Japanese warship; the Japanese Maritime Self-Defense Force's convention has been to reserve names of combat-lost Imperial Navy ships for ships of a significantly larger class than those that had been lost. Sōryū was the first of the Japanese carriers destroyed at Midway in a coordinated American dive-bombing attack; she was the only one of the four Midway carriers to receive her fatal damage in a single concentrated ninety-second bombing sequence. She was, in 1942, the most successful carrier in the world measured by Allied ships sunk by her air group; she became, in the space of ninety seconds, the opening victim of the reversal that broke the Japanese carrier force.