The World’s great Submarines charts the grim battle of attrition which was waged under the waves by German U-boats and Allied submarines alike. Read about U-9, which sank three British cruisers at the beginning of the war; find out about the German campaign in 1940–41 that almost brought Britain to her knees as terrible damage was inflicted on the British merchant fleet. Discover the successful campaign waged by US submarines in the Pacific, and the British X-craft that sunk the Tirpitz.