After the United States entered World War II in December 1941, three Cunard White Star liners, Aquitania, Queen Mary, and Queen Elizabeth, began the epic mission of transporting millions of GIs and British Empire troops across the North Atlantic. Without the protection of naval or air escort, these three ships formed the nucleus of the "Atlantic shuttle service" that relied heavily on speed and decoded Ultra intelligence to avoid potential U-boat traps. This gripping story is based on a secret journal kept by the author, a Royal Australian Navy lieutenant who served as the cipher officer aboard the Aquitania for fifty-three of her Atlantic crossings. His insider's account of the classified sailing conferences and massive logistics obstacles is complimented by light-hearted observations of wartime New York and London. This recounting of a little-known aspect of Battle of the Atlantic is an authoritative, well-illustrated volume that will appeal to everyone interested in one of the great planning feats of World War II.