Allied submarine sunk Japanese merchant ship in the South China Sea according to the U.S. Joint Intelligence Committee Daily summary dated 15 May 1942

An item referred to announcements out of Tokyo, Japan reporting that an Allied submarine sunk on 8 May a large Japanese merchant vessel in the South China Sea despite she was escorted. She was used for transporting laborers to southern regions for economic exploitation purposes.

Source

Map Room Papers (Roosevelt Administration), 1942 - 1945. U.S. Joint Intelligence Committee. Daily summary No. 156 dated 15 May 1942