After the Second World War, Winston Churchill recalled that there was one campaign on which the entire British and indeed Allied effort had depended: “Amid the torrent of violent events one anxiety reigned supreme. Battles might be won or lost, enterprises might succeed or miscarry, territories might be gained or quitted, but dominating all our power to carry on the war, or even keep ourselves alive, lay our mastery of ocean routes and the free approach and entry to our ports.”2 Failure in the Battle of the Atlantic meant failure in the war. It really was as simple as that.
What is not so simple is making sense of the ebbs and flows of the Battle of the Atlantic eighty years later. The battle (really, campaign) began on the first day of the war, when the British and Canadians instituted naval control of shipping, or the convoy system. It lasted until the last week of the war, when American warships sank U-853 off the coast of Rhode Island and an RAF Catalina damaged U-320 off the coast of Norway. In between, thousands of individual battles, many of them now forgotten, were fought across thousands of square miles of ocean. The result is well understood: the Allies defeated the U-boat threat and secured the sea lines of communication between North America and Europe. But when they achieved that goal and how they did it remain questions that animate historians today.
A good starting point for answering those questions is Churchill himself. No person in history has been so well-placed to make sense of them. Not only was he the wartime leader who experienced the victories and defeats at sea in real time, but also after the war he wrote influential and bestselling histories of those events. As he saw it, the Allies won because of the overwhelming, he claimed, “The year 1942 was to provide many rude shocks and prove in the Atlantic the toughest of the whole war.”But in April 1943, he wrote in, “we could see the balance turn.”
