The name “Battle of the Atlantic” was coined by Winston Churchill in February 1941. It has been called the “longest, largest, and most complex” naval battle in history. The campaign started immediately after the European war began, during the so-called “Phoney War“, and lasted six years, until the German Surrender in May 1945. It involved thousands of ships in more than 100 convoy battles and perhaps 1,000 single-ship encounters, in a theatre covering thousands of square miles of ocean. The situation changed constantly, with one side or the other gaining advantage, as participating countries surrendered, joined, and even changed sides in the war, and as new weapons, tactics, counter-measures, and equipment were developed by both sides. The Allies gradually gained the upper hand, overcoming German surface raiders by the end of 1942 and defeating the U-boats by mid-1943, though losses due to U-boats continued until war’s end.