With the fall of France in 1940, the dock took on new strategic importance for the Germans, as it was the only dry dock on the West Coast of France capable of servicing the battleships "Bismarck" and "Tirpitz". The location gave access to the Atlantic Ocean, by-passing the Royal Navy's defensive lines organised along the GIUK gap. "Bismarck" broke into the Atlantic in 1941 but was damaged in the Battle of the Denmark Strait. She was heading for Saint-Nazaire for repair when she was brought to battle by the Royal Navy and sunk, leaving "Tirpitz" as the largest surface threat from the Kriegsmarine.