The first dedicated escorts ? uncomplicated ships designed for convoy ? were developed at the end of World War I, releasing battleships to the business for which there were better suited. The Battle of the Atlantic highlighted the need for ?large corvettes? that combined range and capacity with seaworthiness, simplicity and cheapness, and thus emerged the frigate. With the creation of NATO in 1949, all primarily Anti-Submarine (AS) escorts became generically termed ?frigates?, to distinguish them from ?destroyers? which were configured as Anti-Aircraft (AA). This fully illustrated reference book charts the complete history of frigates, from their post-World War I function as escort vessels, their role as sloops and corvettes, and their subsequent transformation into post-World War II anti-submarine vessels. It focuses on topics relating to frigates? development, for example the submarine threat in 1939, ?Johnny? Walker and the Anti-Submarine Support Group, Escort Carrier Support Groups, and improved weapons, sensors and escorts. A country-by-country directory of over 70 classes describes the main characteristics of each vessel. Each entry, with its expert commentary and high-quality photography, is accompanied by a specification box detailing country of origin, displacement, dimensions, armament, machinery, power, performance and protection. A useful glossary containing definitions of key naval terms is included at the back of the book. With its lively narrative and over 235 photographs, this authoritative volume provides historians and enthusiasts with key information about these important naval vessels.