The Yoshida Maru was a passenger cargo ship built in 1919 by Asano Shipbuilding in Tsurumi, Japan. Taken up by the Japanese Army this was one of many "Hell Ships" used to transport Allied PoWs on the torturous voyages from port to port. In April 1944 she was being used to transport over 2,500 men of the 32nd Infantry Division from Shanghai to Papua New Guinea to reinforce the Vogelkop Peninsula and keep American troops from taking the island and using it as a jumping off point to invade the Philippines. Just one ship in a convoy carrying about 20,000 troops the ships were sighted by an American submarine.

USS Jack SS-259, on her fourth war patrol, sighted the convoy on Apr. 25 at 1247 hrs. An attack by a Japanese aircraft seven hours earlier caused the boat to dive, but when they surfaced about 45 miles west of the northern Luzon coast, Cdr. Thomas M. Dykers was surprised to see seven transports, a number of escort vessels and another aircraft about 12,000 yards away.

Dykers, a two time Navy Cross winner, played a 13 hour cat and mouse game attempting to get his boat into a firing position. Finally at 0133 on April 26, 1944 Dykers fired a salvo of six torpedoes from his forward tubes, using only radar contact for the firing solution as darkness prevented a visual bearing. At 0140 four hits were heard which caused the escorts to begin to drop depth charges in a very erratic fashion. Apparently the Japanese had no idea from which direction the attack had come from.

Dykers reloaded his bow tubes and at 0237 he fired ten more fish at the convoy, Dykers reported six hits on at least three ships, one "made a very fine display of pyrotechnics, apparently as ammunition burned, with one explosion flaring up after another".

At 0310 one of the ships detached from the convoy in an attempt to escape, but unknown to the captain, headed straight toward the waiting submarine. At 0342 a spread of three torpedoes were fired at the approaching ship, Dykers claimed two hits. A fourth torpedo failed to leave the tube and all attempts to fire it failed due to a defect. The submarine submerged at 0449 and the action was finished.

Apparently the only ship sunk was Yoshida Maru, she went down with just less than 2,700 troops and crew, not a single survivor was picked up.