This detailed study of the naval Spanish Civil War describes how the Spanish Navy, torn in two and comprising a Republican and Nationalist part, fought a civil war at sea involving both Hitler's and Mussolini's navies. In July 1936, a pro-fascist coup orchestrated by General Franco tore Spain apart and plunged the country into a bitter civil war. Like Spain itself, the Spanish Navy was torn in two: crews and most ships remained loyal to the Republican government but many of the Navy’s officers joined Franco's rebels, and warships under repair or 'mothballed' in southern ports soon fell to the rebel advance. These formed the basis of Franco’s 'Nationalist fleet,' and with both Italian and German help, the rebels were able to contest the Republic's control of Spanish waters. Overall the Republican Navy held its own, despite mounting losses, until the collapse of the Republican Army led to the fleet seeking internment in French North Africa. Packed with contemporary photographs and full colour illustrations, this study examines the composition and organization of the two rival fleets, the capabilities of their ships and submarines, and the performance of their crews. It also covers the warships of the Basque Auxiliary Navy - an offshoot of the Republican Fleet - and other navies who played a part in the conflict, most notably the Italian Regia Marina.