I’m not super well-versed in the history and don’t know specifically about an incident where Americans shot survivors of their attack, but it’s possible they were thinking of the RMS Lanconia which was shot by a U-boat, which then attempted to coordinate a rescue of both civilian and military survivors (while flying the Red Cross) only to be attacked by American aircraft, forcing the submarines to dive and abandon the people they were attempting to rescue. This led to the Lanconia Order, which forbid rescuing survivors.

[–] Belly_Beanis@hexbear.net 9 points 5 days ago (1 children)

IIRC it was agreed upon international law to both make your presence known prior confronting enemy vessels (anti-piracy laws) and rescue enemy crew of the sunken vessel. Both these things went away when submarines started seeing combat because they defeat the purpose of a submarine. Being able to sink enemy ships undetected kind of made the laws moot to begin with since subs eventually could attack without surfacing.

[–] Trying2KnowMyself@hexbear.net 7 points 5 days ago

In the Lanconia attack, my understanding is that while they of course didn’t broadcast their intention to attack, post-attack the attacking submarine surfaced for the rescue operation, broadcast their location on open radio, and was joined by other submarines in the rescue operation.