This book describes each class of British built sloops built from 1926-1945 and gives a short description of the war service of each of these ships. These were designed and built as anti-sub escort ships, although until about the mid 1930s the designers had dreams that these ships could serve as minesweepers also. It took the British awhile to get the design right, but with the Black Swan Class of 1937 the Royal Navy had a real winner.. In fact, this class and the war built sloops of the Second World War were the best convoy escort ships of any nation in this conflict. With excellant anti-aircraft weapons and an astounding anti-sub ablity, these ships had a impact on the war far in excess that the numbers deployed would suggest. This book gives an excellant overview of each class built and a good, but short, summery of the war service of each ship. There are also photos of each ship. To those interested in the naval war 1939-1945, there is no better book on this subject.