The Shōkaku class (翔鶴型, Shōkaku-gata) consisted of two aircraft carriers built for the Imperial Japanese Navy (IJN) in the late 1930s.

Completed shortly before the start of the Pacific War in 1941, the Shōkaku and Zuikaku were called "arguably the best aircraft carriers in the world" when built.

Two months later, they attempted to support a major offensive by the Imperial Japanese Army to push the United States Marines off Guadalcanal.

No longer restricted by the provisions of the Washington Naval Treaty, which had expired in December 1936, and with relaxed budgetary limitations, the IJN sought qualitative superiority over their foreign counterparts.

To verify these assumptions, the NATD filmed hundreds of takeoffs and landings aboard Akagi in October–November 1938 and decided to move the island over to the starboard side and further forward, about one-third of the length from the bow.

Based on hydrodynamic research conducted for the Yamato-class battleships, the Shōkaku class received a bulbous bow and twin rudders, both of which were positioned on the centerline abaft the propellers.

With a working pressure of 30 kg/cm2 (2,942 kPa; 427 psi), the boilers gave the turbines enough steam to generate a total of 160,000 shaft horsepower (120,000 kW) and a designed speed of 34.5 knots (63.9 km/h; 39.7 mph).

The boiler uptakes were trunked to the ships' starboard side amidships and exhausted just below flight deck level through two funnels that curved downward.

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.

[14] In June 1942, Shōkaku and Zuikaku had their anti-aircraft armament augmented with six more triple 25 mm mounts, two each at the bow and stern, and one each fore and aft of the island.

Historian Alan Zimm said the young aviators delivered "a sterling performance, greatly exceeding expectations and outshining the dive bombers from the more experienced carriers.

"[28] In January 1942, together with Akagi and Kaga of the First Carrier Division, the sisters supported the invasion of Rabaul in the Bismarck Archipelago, as the Japanese moved to secure their southern defensive perimeter against attacks from Australia.

Although the civilian shipping had been evacuated from Colombo harbor, the Japanese sank an armed merchant cruiser, a destroyer, and severely damaged some of the support facilities.

[33] The Kido Butai returned to Ceylon four days later and attacked Trincomalee; the sisters' aircraft sank a large cargo ship and damaged the monitor HMS Erebus.

In the meantime, the Japanese spotted the light carrier HMS Hermes, escorted by the destroyer HMAS Vampire, and every available D3A was launched to attack the ships.

[34] En route to Japan, the Fifth Carrier Division was diverted to Truk to support Operation Mo (the planned capture of Port Moresby in New Guinea).

While they were preparing for the mission, the Americans intercepted and decrypted Japanese naval messages discussing the operation and dispatched the carriers Yorktown and Lexington to stop the invasion.

Alerted by radar, some of the American Combat Air Patrol (CAP) was vectored to intercept the Japanese aircraft, the rest being retained near the carriers because of bad weather and fading daylight.

En route to Japan, Shōkaku was caught in a severe storm and nearly capsized as the weight of the water used to put out the fires had compromised her stability.

[41] Ryūjō was detached early on 24 August to move in advance of the troop convoy bound for Guadalcanal and to attack the American air base at Henderson Field if no carriers were located.

Most of the American carrier aircraft were already airborne by this time, either on CAP, returning from search missions, or from sinking Ryūjō, so only a small airstrike was launched in response to the spot report.

Four days later, the Japanese spotted a small American convoy that consisted of a fleet tug towing a gasoline barge and escorted by the destroyer Meredith.

Shōkaku was badly damaged by six hits from USS Hornet's dive bombers;[46] Zuikaku was not spotted or attacked as she was hidden by the overcast conditions, just like at the Battle of the Coral Sea.

[49] In May, Shōkaku and Zuikaku were assigned to a mission to counterattack the American offensive in the Aleutian Islands, but this operation was cancelled after the Allied victory on Attu on 29 May.

[50] At the beginning of November, the bulk of their air groups were transferred to Rabaul to bolster the defenses there, just in time to help defend the port against the Allied attack a few days later.

The Americans did not spot the Japanese carriers until the afternoon of the following day[57] and launched a large airstrike that only succeeded in hitting Zuikaku with a single bomb that started a fire in the hangar.

[58] In October 1944, Zuikaku was the flagship of Admiral Jisaburo Ozawa's decoy Northern Force in Operation Shō-Gō 1, the Japanese counterattack against the Allied landings on Leyte.

On the morning of 24 October, she launched 10 fighters, 11 fighter-bombers, 6 torpedo bombers, and 2 reconnaissance aircraft[58] as her contribution to the airstrike intended to attract the attention of the American carriers away from the other task groups that were to destroy the landing forces.

[60] The American carriers launched an airstrike shortly after dawn; Zuikaku was struck by three bombs and one torpedo that started fires in both hangars, damaged one propeller shaft, and gave her a 29.5° list to port.

The bombs started fires in the hangars, the torpedoes caused major flooding that increased her list, and the order to abandon ship was issued before Zuikaku sank by the stern.