Hitler in a witness protection program?
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Looks cool enough, probably sourced from some other original document. I didn't find any reference to a U-530 in service but could be wrong. Those things are many things but
small isn't one of them. I find the idea of refueling from 'a sailing vessel' strange but again, could be wrong. I know they had dedicated 'milch cow' subs that were specifically designed for that purpose but wonder if any of their surface combatants could refuel their own subs. For example, destroyers can refuel from larger vessels but I've never heard the practice applied to submarines. Maybe only because the ones we built in that era had extremely long range.