was the lead ship of her class of two aircraft carriers built for the Imperial Japanese Navy (IJN) shortly before the Pacific War. Along with her sister ship , she took part in several key naval battles during the war, including the attack on Pearl Harbor, the Battle of the Coral Sea, and the Battle of the Santa Cruz Islands, before being torpedoed and sunk by the U.S. submarine at the Battle of the Philippine Sea.

Design

thumb|left|Shōkaku being launched in heavy rain at Yokosuka, 1 June 1939.

The Shōkaku-class carriers were part of the same program that also included the s. No longer restricted by the provisions of the Washington Naval Treaty, which expired in December 1936, the Imperial Japanese Navy (IJN) was free to incorporate all those features they deemed most desirable in an aircraft carrier, namely high speed, a long radius of action, heavy protection and a large aircraft capacity. Shōkaku was laid down at Yokosuka Dockyard on 12 December 1937, launched on 1 June 1939, and commissioned on 8 August 1941.

With an efficient modern design, a displacement of about , and a top speed of , Shōkaku could carry 70–80 aircraft. Her enhanced protection compared favorably to that of contemporary Allied aircraft carriers and enabled Shōkaku to survive serious damage during the battles of the Coral Sea and Santa Cruz.

Hull

In appearance, Shōkaku resembled an enlarged , though with a longer overall length, wider beam and a larger island. As in Hiryū, the forecastle was raised to the level of the upper hangar deck to improve seakeeping. She also had a wider, more rounded and heavily flared bow which kept the flight deck dry in most sea conditions.

The carrier's forefoot was of the newly developed bulbous type, sometimes referred to informally as a Taylor pear, which served to reduce the hull's underwater drag within a given range of speeds, improving both the ship's speed and endurance. Unlike the larger bulbous forefeet fitted to the battleships and , however, Shōkakus did not protrude beyond the ship's stem.

thumb|right|The twenty-eight chief shipbuilders of Shōkaku pose at the ship's [[prow prior to launching (30 May 1939).]]

Machinery

The geared turbines installed on Shōkaku were essentially the same as those on Sōryū, maximum power increasing by to . In spite of all the additional armor, greater displacement and a increase in draught, Shōkaku was able to attain a speed of just over during trials. Maximum fuel bunkerage was 4100 tons, giving her a radius of action of at . Two same-sized downward-curving funnels on the ship's starboard side, just abaft the island, vented exhaust gases horizontally from the boilers and were sufficiently angled to keep the flight deck free of smoke in most wind conditions.

Flight deck and hangars

Shōkakus long wood-planked flight deck ended short of the ship's bow and, just barely, short of the stern. It was supported by four steel pillars forward of the hangar box and by two pillars aft.

The flight deck and both hangars (upper and lower) were serviced by three elevators, the largest being the forward one at by , the middle and the rear elevators measured by . All three were capable of transferring aircraft weighing up to and raising or lowering them took approximately 15–20 seconds.

Shōkakus nine Type 4 electrically operated arrester wires followed the same standard arrangement as that on Hiryū, three forward and six aft. They were capable of stopping a aircraft at speeds of . A third crash barrier was added and a light collapsible wind-break screen was installed just forward of the island.

After experimenting with port-side islands on two previous carriers, and Hiryū, the IJN opted to build both Shōkaku and her sister ship Zuikaku with starboard-side islands.

The time required for repairs, combined with the aircraft and aircrew losses incurred by her and Zuikaku, kept both carriers from participating in the Battle of Midway.

Following her return to front-line duty, both Shōkaku and her sister-ship Zuikaku, with the addition of the light carrier , were redesignated as the First Carrier Division and took part in the Battle of the Eastern Solomons, where they damaged , but Shōkaku was in turn damaged by dive bombers of Enterprise, which prevented the bombardment of nearby Henderson Field.

The First Carrier Division subsequently participated in the Battle of the Santa Cruz Islands on 26 October 1942, where they crippled (Hornet was abandoned and later sunk by Japanese destroyers and ). Shōkaku was again seriously damaged, taking at least three (and possibly as many as six) 1,000-lb. bomb hits from a group of fifteen Douglas SBD-3 dive bombers launched from Hornet and . The Type 21 radar, installed a month ago, enabled the early detection of the incoming U.S. planes, so refueling crews were alerted below deck, giving them time to drain and purge the aviation gasoline lines before they were ruptured by bomb hits, thus saving the ship from the catastrophic avgas fires and explosions that caused most of the carrier sinkings in the Pacific theater. Shōkaku was also fortunate as she had few aircraft on board at the time of the attack. As a result, no major avgas fires broke out and her seaworthiness was preserved. Her flight deck and hangars, however, were left in shambles and she was unable to conduct further air operations during the remainder of the battle. The need for repairs kept her out of action for months, leaving other Japanese defensive operations in the Pacific lacking sufficient airpower.

thumb|right|Shōkaku crewmembers fight fires on the flight deck after being hit by American bombs during the Battle of the Santa Cruz Islands

After several months of repairs and training, Shōkaku, now under the command of Captain Hiroshi Matsubara, was assigned in May 1943 to a counterattack against the Aleutian Islands, but the operation was cancelled after the Allied victory at Attu. For the rest of 1943, she was based at Truk, then returned to Japan for maintenance late in the year.

Sinking

In 1944, Shōkaku was deployed to the Lingga Islands south of Singapore. On 15 June, she departed with the Mobile Fleet for Operation "A-Go", a counterattack against Allied forces in the Mariana Islands, resulting in the Battle of the Philippine Sea. Her strike waves suffered heavy losses from U.S. combat air patrols and anti-aircraft fire, but some survived and returned safely to the carrier. One of her D4Y Suisei strike groups, composed of veterans from the Coral Sea and Santa Cruz engagements, broke through and one plane allegedly struck home with a bomb that damaged the battleship and caused many casualties, but this group suffered heavy losses themselves.

Shōkaku was struck at 11:22 on 19 June by three (possibly four) torpedoes from the submarine , under Commander Herman J. Kossler. As Shōkaku had been in the process of refueling and rearming aircraft and was in an extremely vulnerable condition, the torpedo hits started avgas fires that proved impossible to control. At 12:10, an aerial bomb exploded, detonating aviation fuel vapors which had spread throughout the ship. The order to abandon ship was given, but before the evacuation had progressed very far, Shōkaku abruptly took on water forward and sank quickly bow-first at position , taking 1,272 men with her. The light cruiser and destroyers , , and rescued Captain Matsubara and 570 men.