Liste des épisodes

New testimony from British sailors and the U-boat men who hunted them, plus archive material and dramatic reconstructions, illustrate the threat from Churchill's one fear, the hidden enemy under the sea.

In May 1941, listening stations began intercepting messages from U-Boats patrolling in the Atlantic, sent from their Headquarters. If Naval Inteligience could decode them would be able to locate an enemy in 3 million sq miles of ocean.

In 1942; Karl Dönitz commanded 342 U-Boats and hoped to strike a decisive blow on the convoys in which the Allied war depended. Fast on the surface, able to hide beneath it, the U-Boat seemed invincible. This is how the Allies fought back.