In 1942 the British were fighting for control of the Atlantic Ocean.  If they lost this battle they would starve and be put out of the war.  German submarines were pushing the British to their limits and they could ill afford to have the German battleship Tirpitz sortie into the Atlantic and join the fight. To stop this from happening the British determined the best way to neutralize the Tirpitz was to destroy the only dry dock on the Atlantic coast that was large enough to accommodate the battleship should it take damage fighting on the open ocean. The Great Raid of All is the the story of how a small force of British sailors and commandos sailed under the noses of the Germans and destroyed the Normandie dry dock in Saint Nazaire.