Fast, compact and formidable, destroyers were in the thick of the actin in every theatre of operations during World War II. Demands made upon the flotillas were enormous: not only were they to escort the main battle fleets into action, but they were also called upon to escort convoys, protecting their charges against the depredations of aircraft and submarines. The torpedo role dimished and, increasingly, destroyers were called upon to perform a wide range of duties, often of the most hazardous nature. Losses were high. This encyclopedia details all the destroyers extant, completed or laid down during the period 1939-45 by the navies of the world. Each class is described under three headings - design, modifications and service - while full data tabulations are also presented, including builder, laying-down, launcing and commissioning dates, notes on the fate of each ship and particulars including dimensions, armament and performance.