Early in WW2, the Royal Navy viewed Scapa Flow as a protected sanctuary, yet gaps in defenses and degraded barriers left a route open. On the night of October 13 to 14, 1939, U-47 under Günther Prien ...
Dark Seas Official on MSN

Only one submarine ever did this

At 1:04 in the morning on October 14, 1939, HMS Royal Oak shuddered. The battleship was supposed to be riding at anchor, but ...