Operation Chariot succeeded because it was unthinkable

Eighty years ago, just after midnight on 28 March 1942, the British destroyer HMS Campbeltown crept up the estuary of the River Loire towards the heavily defended port of St Nazaire. Here lay an immense dry dock, the only facility on the west coast of France that German battleships such as the ferocious Tirpitz could use if they needed repair. Destroy the dock, and Tirpitz would be unable to sortie against the Atlantic convoys supplying Britain. The only way to do that, however, was to wreck the lock gate at the entrance. And that meant filling a ship with explosives, ramming it into the gate and blowing the whole lot up, while commandos jumped ashore to demolish the pumps, the winding gear and anything else they could.

That was the mission, codenamed Chariot, of the 623 sailors and commandos on board Campbeltown and the flotilla of motor launches she led.