Tang departed Pearl Harbor on 8 June and stalked enemy shipping in the East China Sea and Yellow Sea areas. On 24 June, southwest of Kagoshima, the submarine contacted a convoy of six large ships guarded by 16 escorts. Tang closed for a surface attack and fired a spread of three torpedoes at one of the ships and then fired a similar spread at a second target. Explosions followed, and Tang reported two ships sunk. However, postwar examination of Japanese records revealed by the Japanese government show that two passenger-cargo ships and two freighters were sunk. The ships must have overlapped, and the torpedo spread must have hit and sunk two victims in addition to their intended targets. Those sunk – Tamahoko Maru, Tainan Maru, Nasusan Maru, and Kennichi Maru – added up to 16,292 tons of enemy shipping.[DANFS 1]
TORPEDO SWARM: Whenever this unit makes a Torpedo attack, it may make an additional 1-die Torpedo attack against all other enemy Ships in the same sector.
I would just like to say that Tang's skipper, Richard O'Kane, liked to make very ballsy attacks on convoys while surfaced (the thought being that this is the last place you look for a submarine).
I have no clue what sort of SA would match this, but that is something to think about.
Additionally, a few of her crewmen hold the distinction for the only men to escape a sunken submarine without outside help, swimming about 200 feet up from the sea floor. I don't know if a victory-point SA would be in order for that, but it should at least be in the flavor text.