Soryu

Soryu was a Japanese fleet aircraft carrier of the Second World War, a fast and lightly protected ship built for speed and a large air group rather than for survival under fire. Commissioned in December 1937, she became one of the six carriers of the Kido Butai, the Imperial Japanese Navy strike force that opened the Pacific War with the attack on Pearl Harbor on 7 December 1941. In the first six months of the war Soryu took part in the strike on Pearl Harbor, the raid into the Indian Ocean, and the operations that carried Japanese naval air power from Hawaii to Ceylon. Her career ended at the Battle of Midway on 4 June 1942, when three bombs from dive bombers of USS Yorktown set her ablaze. Fires reached her hangars and fuel systems, the ship lost power, and she sank that evening with the loss of about 711 of her crew. Soryu and her sister Hiryu, sunk the same day, showed both the striking power and the fragility of the early Japanese carrier force.

1. Key Facts

Class/Type	Soryu-class fleet aircraft carrier
Launched	23 December 1935
Commissioned	29 December 1937
Displacement	About 16,200 tons standard; about 19,500 tons full load
Length	227.5 metres
Speed	About 34.5 knots
Complement	About 1,100 officers and men, plus aircrew
Armament	12 x 127 mm dual-purpose guns; 28 x 25 mm anti-aircraft guns
Aircraft	About 57 operational aircraft, with spares bringing the total to about 70
Fate	Sunk by air attack at the Battle of Midway, 4 June 1942

2. Development

The Treaty Carrier

Soryu was designed within the limits set by the Washington Naval Treaty, which capped the total carrier tonnage Japan could build and shaped every Japanese carrier of the 1930s. The navy wanted a ship that carried as many aircraft as possible on a limited displacement, and the designers answered by keeping armour light, machinery powerful, and the hull long and narrow. The result was a carrier of about 16,200 tons standard displacement that could make more than 34 knots, faster than almost any capital ship afloat. The design drew on experience with the earlier carriers Akagi and Kaga, which had been converted from capital ship hulls, and on the small carrier Ryujo. Soryu was the first Japanese carrier built from the keel up as a large fleet carrier under treaty limits, and her layout, with the island on the starboard side and a full-length flight deck, became the pattern for the carriers that followed her.

Construction at Kure

Soryu was laid down at the Kure Naval Arsenal in December 1934 and launched on 23 December 1935. Fitting out took another two years, because the navy used the ship to test new machinery, catapults, and arresting gear. She was commissioned on 29 December 1937, just as Japan was deepening its war in China. Her sister ship Hiryu, built to a modified design at Yokosuka, followed in 1939, and the two are often treated as a class, although their machinery and hull details differed. Soryu’s early service was spent in home waters and off China, where her air group gained experience in operations over land, experience that would matter when the same pilots flew against American ships. By 1941 she was assigned to the First Air Fleet, the carrier strike force assembled under Vice Admiral Chuichi Nagumo, and she trained for the long-range strike that would open the Pacific War.

3. Design

A Fast, Light Hull

Soryu’s design traded protection for speed and aircraft capacity. Her hull was long and fine, driven by four sets of geared steam turbines producing about 152,000 shaft horsepower, which gave her a top speed of about 34.5 knots. That speed let her keep up with cruisers and outrun most battleships, and it gave her the wind over the deck needed to launch fully loaded aircraft. The price was thin armour: her belt was only about 46 millimetres thick in places, and her flight deck had no armour at all. A single bomb that penetrated to the hangar could start fires among fuelled and armed aircraft, and that vulnerability would prove fatal at Midway. Her island was placed on the starboard side, a layout the Japanese navy standardised after experiments with port-side islands on Akagi and Hiryu, and it carried the bridge, funnel, and fire control for the anti-aircraft guns.

Hangars and Flight Deck

Soryu had two hangar decks, served by three lifts, and a flight deck about 217 metres long. Her air group in 1941 numbered about 57 operational aircraft, with additional aircraft carried in crates as spares, for a total of about 70. The usual complement was 21 Mitsubishi A6M Zero fighters, 18 Aichi D3A dive bombers, and 18 Nakajima B5N torpedo bombers, a balanced force that could fight for air superiority, strike ships with bombs and torpedoes, and scout over a wide area. Aircraft were moved between the hangars and the flight deck by lift, armed and fuelled below, and spotted for launch in waves. The system worked well in the calm conditions of the early Pacific campaigns, but it meant that during strikes the hangars were crowded with fuelled aircraft, armed bombs, and torpedoes, a combination that turned a single hit into a disaster.

4. Technical Specifications

Hull and Machinery

Soryu measured 227.5 metres in length, 21.3 metres in beam, and about 7.6 metres in draught at full load. Her standard displacement was about 16,200 tons, rising to about 19,500 tons at full load, although sources differ by a few hundred tons because Japanese displacement figures were calculated under different loading conditions. Her eight boilers fed four turbine sets driving four shafts, and her designed speed of 34.5 knots made her one of the fastest carriers in the world. Her range was about 7,750 nautical miles at 18 knots, enough to cross the Pacific and return, although in practice the Kido Butai depended on oilers for sustained operations far from Japan. Her crew numbered about 1,100 officers and men, with the air group adding several hundred more, so that more than 1,100 men were aboard when she sailed for Midway.

Protection and Seakeeping

Protection was deliberately light. The machinery spaces and magazines were shielded by a belt of about 46 millimetres and a deck of about 25 millimetres over vital spaces, far thinner than the armour of contemporary American and British carriers. The navy accepted this because treaty tonnage was scarce and because Japanese doctrine expected the carrier’s aircraft to keep enemy ships and aircraft at a distance. In heavy seas Soryu was a good sea boat, although her narrow hull rolled in a swell, and her high speed made her wet forward in bad weather. Her steering and stability were adequate for fleet operations, and she could turn inside most battleships. The weakness was not in her handling but in her damage control: her fire mains, ventilation, and hangar arrangements made it hard to fight a large fire once it had taken hold, and her crew had less training in damage control than their American counterparts.

5. Armament and Aircraft

Guns and Anti-Aircraft Defence

Soryu carried 12 127 mm dual-purpose guns in six twin mounts, three on each side of the flight deck, which could engage both surface targets and aircraft. For close-range air defence she carried 28 25 mm anti-aircraft guns in twin mounts, a weapon that proved disappointing in service because of its short range, low rate of fire, and slow training. The Japanese navy relied on the fighter screen to protect its carriers, and Soryu’s own guns were a last line of defence rather than a serious barrier. By 1942 the American carrier air groups were learning to attack in coordinated dive-bomber and torpedo strikes, and a carrier that depended on fighters alone was vulnerable when its combat air patrol was drawn away. At Midway, Soryu’s fighters were engaged elsewhere when the American dive bombers arrived, and her guns could not stop them.

The Air Group

Soryu’s air group was the heart of the ship. In December 1941 it consisted of 21 Zero fighters, 18 D3A dive bombers, and 18 B5N torpedo bombers, with spares. The Zero was the finest carrier fighter in the Pacific in 1941, faster and more manoeuvrable than anything the Americans flew, and the D3A and B5N were proven strike aircraft. The pilots were among the most experienced in the Japanese navy, many of them veterans of China. The air group could launch a strike of about 50 aircraft, enough to cripple a battleship force or a small carrier group. Its weakness, which became clear as the war went on, was the loss of trained pilots: Japan had no system for replacing experienced aircrew at the rate the war demanded, and the men who flew from Soryu at Pearl Harbor were, in many cases, irreplaceable.

6. Service History

Pearl Harbor and the Early Offensives

Soryu sailed with the Kido Butai in November 1941 for the strike on Pearl Harbor. Her aircraft took part in both waves of the attack on 7 December, her torpedo bombers striking battleships and her dive bombers hitting airfields and other targets. The attack crippled the American battleship fleet but missed the American carriers, which were at sea. In the months that followed, Soryu supported the invasions of the Dutch East Indies and took part in the raid on Darwin, Australia, in February 1942. In April 1942 she joined the Indian Ocean raid, in which Japanese carriers sank the British carrier Hermes, two cruisers, and other ships off Ceylon. The raid showed the reach of Japanese naval air power, but it also kept the carriers at sea for long periods, wearing out aircraft and crews, and it delayed the refit that Soryu needed.

The Road to Midway

After the Indian Ocean raid, Soryu returned to Japan for a brief refit and then sailed for Midway in May 1942 as part of Admiral Isoroku Yamamoto’s plan to draw out and destroy the American carriers. The Japanese plan assumed the Americans would react to an invasion of Midway, and that the Kido Butai, with four carriers, would ambush them. American codebreakers had read enough of the Japanese plan to set their own ambush, and three American carriers waited northeast of Midway. On the morning of 4 June 1942, Soryu launched strikes against Midway Island, and her aircraft were being refuelled and rearmed for a strike against the American carriers when the American dive bombers arrived. The timing of that attack, and the state of Soryu’s hangars, decided her fate in minutes.

7. Notable Actions

The Strike on Pearl Harbor

Soryu’s aircraft flew in the first wave at Pearl Harbor, her B5N torpedo bombers attacking battleships in the harbour while her D3A dive bombers struck airfields. The attack was a tactical success: eight American battleships were damaged or sunk, more than 180 American aircraft were destroyed on the ground, and the Japanese lost only 29 aircraft in total across the whole force. Soryu’s contribution was part of a coordinated strike that had been rehearsed for months, and it showed the power of a carrier force used as a single weapon. The strategic failure, the absence of the American carriers and the survival of the oil tanks and repair yards, was not apparent to the pilots who returned to Soryu that morning. For the Japanese navy, Pearl Harbor was proof that the carrier had replaced the battleship as the decisive weapon at sea.

The Indian Ocean Raid

In April 1942 Soryu took part in the raid into the Indian Ocean, the furthest westward operation of the Kido Butai. On 5 April her aircraft struck Colombo, Ceylon, and on 9 April they attacked Trincomalee, sinking the British carrier Hermes and the destroyer Vampire. The raid sank more than 20,000 tons of British shipping and forced the British Eastern Fleet to withdraw to East Africa. It was the high point of Japanese naval expansion, and Soryu’s air group performed well, but the operation also exposed the limits of Japanese logistics: the carriers could not stay in the Indian Ocean, and the British, although driven off, were not destroyed. Within two months Soryu would be gone, and the Indian Ocean raid would stand as the last great success of the force she served in.

8. Fate

Sunk at Midway

On 4 June 1942, at about 10:25, dive bombers from USS Yorktown found Soryu with her hangars full of fuelled and armed aircraft. Three bombs struck the ship: one on the forward lift, one on the flight deck, and one in the hangar. Fires spread rapidly through the hangar decks, and explosions from bombs and torpedoes wrecked the ship from inside. The fire mains were damaged, the ship lost power, and the crew could not control the blaze. Captain Ryusaku Yanagimoto ordered the ship abandoned, although he himself remained aboard and went down with her. Soryu drifted, still burning, through the afternoon, and sank at about 19:13. About 711 of her crew of about 1,103 were killed, including many of her experienced aircrew and mechanics. The destroyers Isokaze and Hamakaze rescued the survivors.

Aftermath for the Japanese Navy

The loss of Soryu and her three sister carriers at Midway, Akagi, Kaga, and Hiryu, destroyed the core of Japanese naval aviation in a single day. Japan still had carriers under construction, but it had lost the trained air groups that made them effective, and it never recovered the advantage in carrier aviation. The Japanese navy continued to build carriers, including Taiho and the Shinano, but the pilots who flew from them were not the equals of the men lost at Midway. Soryu’s wreck has never been located with certainty, although surveys in the Midway area have identified wrecks of other carriers from the battle. Her name was not reused for a later Japanese carrier, and her loss remains one of the four carrier sinkings that mark the turning point of the Pacific War.

9. Legacy

Lessons in Carrier Design

Soryu’s loss, together with the loss of her sisters at Midway, taught every navy the same lesson: a carrier’s survival depends on damage control, protected fuel systems, and armoured hangars as much as on the number of aircraft she carries. The American navy, which had already begun to build carriers with better fire protection and damage control, drew the lesson from Midway and applied it to the Essex class, which became the most successful carrier design of the war. The Japanese navy, by contrast, continued to build fast carriers with light protection, and Taiho, its first armoured carrier, was lost to a single torpedo because of poor damage control. Soryu’s design, fast and lightly armoured, belonged to an era when carriers were expected to strike first and avoid being hit, and Midway showed that no carrier could rely on that.

Memory and the Kido Butai

Soryu is remembered as one of the six carriers that opened the Pacific War and as one of the four lost at Midway, the battle that ended Japan’s offensive. Her pilots are remembered in Japan as part of the generation of naval aviators who dominated the Pacific in 1941 and 1942 and were largely gone by 1943. The ship appears in histories of Pearl Harbor, the Indian Ocean raid, and Midway, and her loss is often used to illustrate the speed with which naval power could be destroyed in the age of the aircraft carrier. For the study of naval warfare, Soryu stands as an example of a ship that was superbly effective as an offensive weapon and fatally vulnerable once its air group was caught on deck, a balance that defined carrier warfare for the rest of the Second World War.

10. Frequently Asked Questions

What was Soryu?

Soryu was a Japanese fleet aircraft carrier commissioned in December 1937, the first Japanese carrier built from the keel up as a large fleet carrier under the Washington Naval Treaty limits. She was designed for speed and a large air group rather than protection, with a long, narrow hull, thin armour and an unarmoured flight deck. She became one of the six carriers of the Kido Butai, the strike force that opened the Pacific War at Pearl Harbor, and she also took part in the Indian Ocean raid. Her career ended at Midway on 4 June 1942, when dive bombers from USS Yorktown sank her.

How was Soryu sunk?

Soryu was sunk at the Battle of Midway on 4 June 1942, when dive bombers from USS Yorktown found her at about 10:25 with her hangars full of fuelled and armed aircraft being prepared for a strike against the American carriers. Three bombs struck the ship, one on the forward lift, one on the flight deck and one in the hangar, and fires spread rapidly through the hangar decks. Explosions from bombs and torpedoes wrecked her from inside, the fire mains were damaged, and the crew lost power and could not control the blaze. She drifted, still burning, through the afternoon and sank at about 19:13.

How many aircraft did Soryu carry?

Soryu carried about 57 operational aircraft, with spares carried in crates bringing the total to about 70. Her usual air group in 1941 was 21 Mitsubishi A6M Zero fighters, 18 Aichi D3A dive bombers and 18 Nakajima B5N torpedo bombers, a balanced force that could fight for air superiority and strike ships with bombs and torpedoes. The Zero was the finest carrier fighter in the Pacific in 1941, while the D3A and B5N were proven strike aircraft flown by some of the most experienced pilots in the Japanese navy. They were moved by three lifts between two hangar decks and a flight deck about 217 metres long.

How fast was Soryu?

Soryu could make about 34.5 knots, which made her one of the fastest carriers in the world and faster than almost any capital ship afloat. Her four sets of geared steam turbines produced about 152,000 shaft horsepower, driving a long, fine hull that let her keep up with cruisers and outrun most battleships. That speed also gave her the wind over the deck needed to launch fully loaded aircraft, a vital advantage for a carrier whose striking power depended on her air group. Her range was about 7,750 nautical miles at 18 knots, enough to cross the Pacific, although she depended on oilers far from Japan.

How many crew were lost when Soryu sank?

About 711 of her crew of about 1,103 were killed at Midway, a loss that included many of her experienced aircrew and mechanics, men who were difficult for Japan to replace. Captain Ryusaku Yanagimoto ordered the ship abandoned, although he himself remained aboard and went down with her. Soryu drifted, burning, through the afternoon before sinking at about 19:13, and the destroyers Isokaze and Hamakaze rescued the survivors. The loss was part of a larger disaster for Japan that day, since Soryu and her three sister carriers at Midway, Akagi, Kaga and Hiryu, were all destroyed, taking with them the trained air groups that had made Japanese carrier aviation effective.

What happened to Soryu’s sister ship Hiryu?

Hiryu, Soryu’s sister ship, was also sunk at Midway on 4 June 1942, by dive bombers from USS Enterprise. She had been built to a modified design at Yokosuka and followed Soryu into service in 1939, and the two are often treated as a class, although their machinery and hull details differed. Both ships were lost on the same day, together with Akagi and Kaga, in a day that destroyed the core of Japanese naval aviation. Japan still had carriers under construction, but it had lost the trained air groups that made them effective, and it never recovered the advantage in carrier aviation.

11. Sources

1. Wikipedia, “Japanese aircraft carrier Soryu” — construction, specifications, Pearl Harbor, Midway, and sinking.
2. Mark Stille, “Imperial Japanese Navy Aircraft Carriers 1921-45” (Osprey, 2005) — design, air group, and service.
3. Jonathan Parshall and Anthony Tully, “Shattered Sword: The Untold Story of the Battle of Midway” (Potomac Books, 2005) — the Midway attack and the loss of Soryu.
4. Hansgeorg Jentschura, Dieter Jung, and Peter Mickel, “Warships of the Imperial Japanese Navy, 1869-1945” (Naval Institute Press, 1977) — specifications and construction data.
5. Combinedfleet.com, “Soryu” tabular record of movement — service history and movements.
6. Paul S. Dull, “A Battle History of the Imperial Japanese Navy (1941-1945)” (Naval Institute Press, 1978) — operations and strategy.