The Story of How IJN Shōhō Became the First Japanese Aircraft Carrier Sunk in WWII

On May 7, 1942, during the Battle of the Coral Sea, a light Japanese carrier met its end in a violent clash with American carrier forces. The ship was Shōhō, and her sinking made history as the first Japanese aircraft carrier lost in the war. Her short service, hurried design, and dramatic destruction reflect the risks faced by light carriers in an age dominated by naval air power.

This is the story of Shōhō, from her beginnings as a support vessel to her last moments beneath the waters of the Coral Sea.

From Submarine Tender to Carrier

Shōhō did not begin life as an aircraft carrier. Laid down in 1934 and launched in 1935, she was first built as a submarine support ship named Tsurugisaki. Japanese planners, however, had designed her with conversion in mind. By classifying her as an auxiliary vessel, they could bypass treaty restrictions and keep her ready for wartime rebuilding.

In 1940, she entered the shipyard for major reconstruction. Her superstructure was stripped away, a full-length flight deck added, and hangars installed below. Her engines were upgraded to steam turbines, giving her enough speed to work alongside larger fleet units. Renamed Shōhō, meaning “Auspicious Phoenix,” she became a light carrier of modest size compared to Japan’s fleet carriers.

Design and Armament

After conversion, Shōhō measured about 674 feet in length and displaced around 11,400 tons. She could carry about 30 aircraft, supported by two elevators that connected the hangar to her deck. With no island structure, her flight control was managed from below decks, which made operations more difficult.

Her defenses were light. She carried eight 5-inch dual-purpose guns and a limited number of 25mm anti-aircraft guns. A brief refit in April 1942 added more of the smaller weapons, but her overall protection was thin. She had no armored flight deck and relied on maneuvering for survival, a gamble that would soon be tested.

Early Service

Shōhō was commissioned as a carrier on November 30, 1941, just days before the Pacific War began. Under Captain Isawa Ishinosuke, she joined the Fourth Carrier Division with her sister ship, Zuihō. In her early months, she mainly served as an aircraft transport, ferrying fighters to forward bases such as Truk and Rabaul.

Her first taste of combat came in April 1942 when she deployed in response to the Doolittle Raid, though she never engaged the American carriers. Soon after, she was assigned to Operation MO, the plan to capture Port Moresby in New Guinea. For this task she embarked a small air group, including older fighters and torpedo bombers, to provide convoy cover.

Approaching the Coral Sea

In early May 1942, Shōhō joined Rear Admiral Gotō’s covering force for the Port Moresby invasion fleet. On May 6, she was spotted and lightly attacked by American bombers, but escaped without damage. Unknown to her crew, however, American carriers Lexington and Yorktown were closing in.

The following morning, both sides launched search planes. By 7:30 a.m., American scouts reported sighting Japanese ships near Shōhō. Believing they had found the main carrier force, Admiral Frank Jack Fletcher ordered a full strike. Over 90 aircraft took off, heading for what turned out to be Shōhō alone.

The Attack Begins

By late morning on May 7, Shōhō was escorting the invasion convoy under cloudy skies. Her combat air patrol was minimal—only three fighters were airborne when American planes appeared. Without radar, her lookouts gave the first warning as dive bombers descended from above.

The opening attacks missed, but more American planes were already diving. At 11:18 a.m., bombs tore into her deck, one penetrating into the hangar and igniting fuel and aircraft. Fires spread rapidly. Then came the torpedo planes, attacking from both sides. Multiple torpedoes slammed into her hull, flooding engine rooms and crippling her steering.

Final Strikes

Shōhō was now burning and nearly powerless, but the assault was not finished. Aircraft from Yorktown arrived minutes later, dropping more bombs that ripped apart her deck and set off further explosions. Additional torpedo attacks followed, compounding the damage.

Survivors recalled flames engulfing the ship, with ammunition and fuel erupting in violent bursts. American fighters swept away the last Japanese planes in the air. At 11:31 a.m., Captain Isawa ordered abandon ship. Crewmen leapt into the sea as the carrier listed and slowed. Just four minutes later, Shōhō sank stern-first into the Coral Sea.

Loss and Rescue

More than 800 men were on board. Only about 200 survived to be picked up later by the destroyer Sazanami. The rest perished in the sinking or the sea. For the Japanese Navy, the loss of Shōhō was severe, not only for the ship but for the many trained crew members who went down with her.

For the Americans, her sinking was a morale boost after months of setbacks. It showed that Japanese carriers could be destroyed when found and attacked with strength. For Japan, it was a reminder of the vulnerability of lightly protected carriers when caught unsupported.