After losing the Battle of Britain in 1940, Germany tried to defeat Britain by sinking its merchant shipping and starving the people. This was mainly the task of the Navy's U-boats (Submarines) and their commander, Admiral Dönitz. In 1936 Germany had signed an agreement that Merchant Navy personnel must be safeguarded before their ships were sunk, but Hitler and Dönitz didn’t stop their attacks. As the passage of the Channel was closed to the …showed first 75 words of 425 total…

…showed last 75 words of 425 total…than if they sailed independently. But by 1939 there were not enough escorts, and ships with speeds greater than 5 knots were encouraged to sail independently. The German U-boats concentrated on ships that were not in convoy. In the end the U-boats were defeated. The British started dropping depth charges, and attacked by air. That with the use of convoys helped Britain protect itself from the German U-boats. World Book Encyclopedia, Volume 18, 1988 U-boat, under the Swastika, Showell, 1973