BBC History of World War II

An examination of the campaign fought by German U-boats to sever Britain's seaborne supply routes between 1939 and 1942.

How the allied forces fought back against the German U-Boats that had sunk more than 3 million tons of shipping in ther first 18 months of war. Allied intelligence was greatly helped by the capture of cipher material and an Enigma code machine.

In the first three years of war, German U-boats threatened to starve Britain into submission, but by the spring of 1943 the tide had turned. Eyewitness testimonies, archive film and reconstructions illuminate the story of how, in just a few months, the Allies destroyed the U-boat fleet.