The Mediterranean U-boat Campaign lasted approximately from 21 September 1941 to May 1944. Germany's Kriegsmarine aimed at isolating Gibraltar, Malta, and the Suez Canal so as to break Britain's trade route to the far east. More than 60 U-boats were sent to disrupt shipping in the sea, although many were attacked in the Strait of Gibraltar, which was controlled by Britain (nine boats were sunk while attempting the passage and ten more were damaged).