The ships' primary purpose was to protect convoys from submarines. Their performance in that role was imperfect, but participation in attacks does not by itself establish whether a submarine was sunk. Lost Japanese records and the difficulty of explaining a submarine's disappearance limit firm conclusions. Six Etorofu-class ships are said to have been sunk by American submarines. A persistent shortage of escorts also prevented routine use of two or three ships together against one contact.
Notable Point · 20:53-22:19
Convoy defence and uncertain evidence of success
An escort's convoy-defence task is separated from independent submarine hunting, while missing records complicate judgements of its results.