Günther Prien's boat entered an anchorage that Admiral Forbes had partly emptied because he considered it unsafe. HMS Belfast and the seaplane tender HMS Pegasus remained with Royal Oak, and Prien misidentified the battleship as HMS Repulse. The first torpedo strike severed the anchor chain but was mistaken for an internal accident like the explosion that had destroyed HMS Vanguard. That interpretation allowed U-47 to turn, reload, and deliver a devastating second salvo. Royal Oak then lost power, flooded through open portholes as she listed, and sank in about thirteen minutes after the second attack. The stated death toll is 835, including 144 boy seamen under eighteen, making the human cost inseparable from the tactical account. The episode connects the disaster to neglected harbor defenses and the missed opportunity for immediate watertight and anti-submarine action.
Chapter · 2:13:51-2:24:02
U-47 turns a neglected harbor into a disaster
U-47 passed gaps in the old blockship defenses, then a second torpedo salvo sank Royal Oak after the first strike was mistaken for an internal accident.