On 17 September 1942 Admiral Karl Donitz, C-in-C U-boats, issued the following directive: To all Commanders - ‘All attempts to rescue members of ships sunk, therefore also fishing out swimmers and putting them into lifeboats, righting capsized lifeboats, handing out provisions and water, have to cease. Rescue contradicts the most fundamental demands of war for the annihilation of enemy ships and crews’. This order ended what had hitherto been a war in which the opposing factions treated each other with a certain respect, seaman to seaman, showing mercy where mercy was due. It also marked the point at which the Battle of the Atlantic became a dirty war of attrition, with the U-boats hunting in packs snarling and snapping at the heels of the hard-pressed convoys. Ships began to go down like corn before the reaper, men were dying in their hundreds in the cold grey waters of the great ocean. This was a battle without quarter. A battle the U-boats would have won had it not been for the grit and determination of the convoy escorts and the unflagging resilience of the men who manned the vulnerable merchant ships.