You have to put yorself in the shoes of a true german sub commander.
Your stationed in France or Italy, away from your family in Berlin, Bonn, Or Bremen. But you know that every day enemy bombers are pounding your home town. You also know that the fuel, parts, bombs, bullets, oil, and personnel that keeps the enemy planes in the sky is flowing into Britain on any tramp steamer that will stay afloat.
For you the choice is simple. You don't care who the sailors are... Nor do you care if they are "soldiers" or not... The one thing you know is that your wife and children are having to seek shelter from falling bombs and the only real thing you can do about it is seek out the enemy supply ships and sink them.
You comfort yourself in the thought that maybe the ship you just sunk contained the very bomb which was destined to fall on your house back in Bremen.
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