During the two World Wars, German submarines sank over 8000 merchant vessels grossing more than 27 million tons. U-boats twice came close to bringing Britain to defeat. In World War II the battle for supremacy was hard fought, won only at great cost, as techincal advances swayed the advantage from one side to another. U-boats became faster and better armed, while detection and anti-submarine weapons developed apace. It took time to realize that escorted convoys provided the only real security for merchantment. This book tells the twin stories of the Battles of the Atlantic. Strategic failings, on both sides, became apparent at almost every turn. Eyewitness accounts of submarine operations, a discourse on the art of submarine command by a U-boat ace, and extracts from contemporary German naval documents underline the reality of the U-boat wars.