Afterwards, her aircraft were disembarked several times in mid to late 1943 and used from land bases in a number of battles in the South West Pacific.

In the mid-1930s, the Imperial Japanese Navy decided to build a class of two submarine tenders which could be converted into light aircraft carriers or fleet oilers.

As part of their conversion, their original diesel engines, which had given them a top speed of 29 knots (54 km/h; 33 mph), were replaced by a pair of destroyer-type geared steam turbine sets with a total of 52,000 shaft horsepower (39,000 kW), each driving one propeller.

The boilers exhausted through a single downturned starboard funnel and the ships carried 2,642 tonnes (2,600 long tons) of fuel oil, giving them a range of 7,800 nautical miles (14,400 km; 9,000 mi) at a speed of 18 knots (33 km/h; 21 mph).

[1] The primary armament consisted of eight 40-caliber 12.7 cm Type 89 anti-aircraft (AA) guns in twin mounts on sponsons along the sides of the hull.

[5] The ships were also initially equipped with four twin 25 mm Type 96 light AA guns, also in sponsons along the sides of the hull.

Covering the other elements of Operation MO was the Striking Force that consisted of the fleet carriers Shōkaku and Zuikaku.

US Army Air Force (USAAF) aircraft spotted Shōhō[Note 1] southwest of Bougainville Island on 5 May, but she was too far north to be attacked by the American carriers, which were refueling.

[14] That day, Rear Admiral Frank Jack Fletcher received Magic intelligence that placed the three Japanese carriers known to be involved in Operation MO near Bougainville, and predicted 10 May as the date of the invasion.

Based on this information, Fletcher planned to complete refueling his ships on 6 May and move closer to the eastern tip of New Guinea to be in a position to locate and attack Japanese forces on 7 May.

[15] American reconnaissance aircraft reported two Japanese heavy cruisers northeast of Misima Island in the Louisiade Archipelago off the eastern tip of New Guinea at 0735 and two carriers at 0815 on 7 May.

These penetrated the ship's flight deck and burst inside her hangars, setting the fueled and armed aircraft there on fire.

The Japanese and American carrier forces discovered each other in the early morning of 26 October during the Battle of the Santa Cruz Islands and each side launched air strikes.

Upon arrival she was assigned to the Second Carrier Division to provide cover for the evacuation of Guadalcanal, along with Jun'yō and Zuikaku, later in the month and in early February.

That day the American carriers raided the Gilbert Islands and were gone by the time the Japanese reached Eniwetok on 20 September.

Skate unsuccessfully attacked Zuihō on 30 November, while Sailfish torpedoed and sank Chūyō five days later with heavy loss of life.

The new base was closer to the oil wells in Borneo on which the Navy relied and also to the Palau and western Caroline Islands where the Japanese expected the next American attack.

However, the location lacked an airfield on which to train the green pilots and American submarines were very active in the vicinity which restricted the ships to the anchorage.

Zuihō and her consorts were intended to draw the attentions of the Americans while the other carriers conducted their air strikes without disruption.

The Americans discovered the retiring Japanese fleet during the afternoon and Vice Admiral Marc Mitscher ordered an air strike launched.

[31] After reaching Japan on 1 July, the ship remained in Japanese waters until October,[8] training replacements for her air group.

[32] Most of these aircraft were lost for little gain as the Americans suppressed Japanese defenses in the Philippines, preparatory to the actual invasion.

[34] On 18 October, Admiral Soemu Toyoda activated the naval portion of the defense plan after receiving reports of the landings on Leyte.

This accomplished little else as the Japanese aircraft failed to penetrate past the defending fighters; the survivors landed at airfields on Luzon.

They finally found them at 1605, but Admiral William Halsey, Jr., commander of Task Force 38, decided that it was too late in the day to mount an effective strike.

He did, however, turn all of his ships north to position himself for a dawn attack on the Japanese carriers the next day in what came to be called the Battle off Cape Engaño.

Zuihō attempted to launch her few remaining aircraft, but was hit by a single bomb on her aft flight deck after a number of torpedo-carrying Avengers missed.

Zuihō was forced to reduce speed to 12 knots (22 km/h; 14 mph) and flooding increased so that all available hands were ordered to man the pumps at 1410.