Did the sinking of Royal Oak show that older battleships were unsafe even in home waters?
Short answerIt chiefly showed that Scapa Flow's anti-submarine defences were outdated and required urgent improvement.
NotesRoyal Oak's sinking showed that Scapa Flow's barriers and anti-submarine arrangements urgently needed improvement. The German penetration was difficult and was achieved only once, so it was neither effortless nor readily repeatable. Royal Oak's presence also limited the immediate damage, because a later attempt might have found more capital ships in harbour. The condition of the base's layered defences mattered more than the age of the victim.