Traditionally the reason for not allowing enemies to escape is that they will regroup and fight you again (accepting surrender, or allowing parachutists to land & become POWs, is a different matter). In this case, the escaped crew was able to return to bomb German civilians.
Traditionally the reason for not allowing enemies to escape is that they will regroup and fight you again (accepting surrender, or allowing parachutists to land & become POWs, is a different matter). In this case, the escaped crew was able to return to bomb German civilians.