Attack in the East China Sea
On February 27, 1944, returning through the East China Sea, Grayback expended her last two torpedoes in sinking the cargo ship Ceylon Maru. She did not report this sinking, and was never heard from again. ... Post-war study of Japanese records indicated that an ASW aircraft spotted a surfaced submarine that same day on Graybackâ€™s intended track and attacked with bombs. The reports note that the submarine exploded and sank immediately. Subsequent depth charge attacks by surface units brought up a trail of bubbles and a heavy oil slick. ... Grayback completed nine patrols before being lost on the tenth, her most successful. She accounted for a confirmed total 13 1/2 ships, (63,850 tons), including the IJN submarine I-18. This placed her number 20 in the list of high scoring Pacific submarines.