When I was in middle school, we read a story in history class about two submarines who I think were surfaced while they were battling. So, I don't think that torpedoes were used. During the battle one of the submarines thought they had won the battle for whatever reason, I think they thought the other submarine surrendered. So, they started leaving the battle since they thought they had won. The other submarine saw that the other submarine was leaving so then they thought that the other submarine had surrendered, so they thought that they had won. Both submarines thought they had won when neither of them won.