Submarines and the World Wars: The History of Submarine Warfare in World War I and World War II

During World War I, German U-boats operated solo except on one occasion. Initially, the British and nations supplying England with food and materiel scattered vessels singly across the ocean, making them vulnerable to the lone submarines. However, widespread late war re-adoption of the convoy system tipped the odds in the surface ships' favor, as one U-boat skipper described: “The oceans at once became bare and empty; for long periods at a time the U-boats, operating individually, would see...