THE BATTLE OF THE ATLANTIC was the longest single campaign of World War Two, and the most bloody and bitter of them all. U-Boat â€˜Wolf packsâ€™ played a deadly game of cat and mouse with the merchant convoys on which Britain depended for its very survival. One quarter of all British merchant seamen lost their lives â€“ a higher proportion than any of the fighting services. Losses on the German side were appalling too; in 1943, the average U-Boat had a life expectancy of just three or four patrols â€“ and its crewmen a one in three chance of getting out alive. Of the 1,131 commissioned, 735 failed to return. The U-Boat menace started almost immediately war broke out and rapidly grew into the single greatest threat to Britain. In just three nights in October 1940, three convoys lost 38 ships to the Wolf packs. By the end of the year, 1,281 shops had been sunk. To counter the U-Boat menace, Britain expanded the role of Coastal Command using Catalinas and Liberators to provide range escorts, but bombing the concrete U-Boat pens proved futile and U-Boat production increased at a frantic pace. In the last six months of 1942 they sank 3 million tonnes of shopping but, at last, the tide was beginning to turn. Britain had secretly cracked the â€˜Enigmaâ€™ codes and Allied air and sea forces were proving far more effective at hunting down and sinking the U-Boats. In May 1943, 41 U-Boats were sunk for the loss of just 50 merchant ships and, by 1944, the life expectancy of an operational U-Boat had fallen to 1 to 2 missions. In August that year, the RAF 617 â€˜Dambusterâ€™ squadron finally succeeded in smashing the heavily reinforced concrete U-Boat pens with 11,000lb. Tall Boy bombs. With no safety now at sea or in dock, the U-Boat menace was effectively over. THE BATTLE OF THE ATLANTIC tells the complete story of the campaign from start to finish with some of the best available footage of the hardest of all battles and interviews with veterans from both sides.