A warship designer and well-known author of a quartet of books on British warships, David K. Brown takes a detailed look at the Allied ships, weapons, and tactics that won the submarine war in the Atlantic in this handsomely illustrated book. Beginning with the lessons learned from World War I, the author outlines inter-war developments in technology and training and describes preparations for World War II. He then examines the balance of advantage as it see-sawed between U-boats and escorts when new weapons and sensors were introduced at a rapid rate. For defending navies, the prime requirement was numbers, and Brown explains that the most pressing problem was to improve capability without sacrificing simplicity and speed of construction. The author's analyses of the resulting designs of sloops, frigates, corvettes, and destroyer escorts, and his determination of their relative effectiveness, offer insights new even to those well versed on the subject of anti-submarine warfare during the Atlantic War, a campaign that Winston Churchill famously claimed was the only one that really frightened him.