Although the defeat of Japan was the US Navy's greatest contribution to the Second World War, it also played a significant role in the battle against Hitler. Even before Germany declared war in 1941, US naval vessels were actively engaged in Atlantic convoy battles, and suffered their first casualties long before the Pearl Harbor attack formally pitched America into the conflict. Thereafter the US Navy immediately sent reinforcements to the over-stretched Royal Navy, taking part in attacks on German-occupied Norway, flying aircraft to Malta and Egypt from its carriers and adding protection to the convoys to Russia. Its involvement in the crucial Battle of the Atlantic was also substantial, and the invasions of North Africa and Europe from 1942 onwards would have been unthinkable without the massive US forces. As late as 1945 the crossing of the Rhine by the Allied armies was heavily dependent on US Navy assets and expertise. It is not surprising that the Pacific campaign should have received so much attention from naval historians, but as a result the European effort has been undervalued and largely side-lined. This book is intended to redress the balance – not just to chronicle the many little-known US operations in the Atlantic, Arctic and Mediterranean, but to reach a more rounded judgment of the US Navy's contribution to victory in Europe.