Actually, I knew a gentleman in Texas back in the 70s who had first come to this country as a prisoner of war. He had been a diesel mechanic on a U-boat that run afoul of allied depth charges. He was fortunate enough to be sent to Amarillo rather than the briny deep (though some might dispute this order of preference) and eventually was allowed to work outside the camp on daily parole.
Given his skills, he was put to work at a railroad shop and they decided to keep him on when the war finally ended. He did have to return to Germany for a while to get the paperwork straight though.