And I might throw in a bit about the Laconia Incident.
Werner Hartenstein, Commander of a German U-boat in the opening stages of the war, sunk the ship Laconia, which, unaware to him, was carryign civilians. He was left with thousands floudering around.
He picked almost all tof them up, in the U-boats strage, on deck, and towing the lifeboats.
He flew the Red Cross, and got of the coast of Africa.
He radiod a non-encrypted message to allied forces, promising not to attack if they picked the prisoners up.
However , an allied (American, possibly?) aircraft attacked the sub, causing it to jettison the lifeboats, and crash dive.
This actually prompted Karl Doenitz's "Laconia Order" which stipulated no prisoners should be taken from sinking ships, and U-boat menshould not assist drifters, which had been common until then.