This is a history of the development and operation of the Allied convoy system in the Second World War. It explains the organization and protection of convoys and provides descriptions of all the escort vessels, oilers, rescue ships and salvage tugs that were employed. Further explanations are provided on the tactics and weapons of the U-boat war. Also included is an appendix listing every North Atlantic-related convoy, with details of departure and arrival dates and the ships involved, and an index of ships lost.