Staplehurst (Kent), 1st ed., 2004. Xxiii + 276 pp., 20 photo-plates + 7 maps & diagrams. D.j., 24 x 16cm. FINE. The arrival on the stage of submarine warfare during the First World War posed a major threat to Allied shipping and many counter-measures were introduced including the famous Q-Ships or Mystery Ships as they were generally known ; innocent-looking merchantmen that were in fact heavily-armed and naval-manned decoys laying in wait for unsuspecting U-boats that preferred to attack on the surface in those early days. During the Second World War the convoy system was brought into being immediately and carried vital war supplies over from North America ; kept the Mediterranean open ; and fought their way to Russia to supply the Soviet Army with the means to counter the Nazi invasion. German commerce raiders were highly successful and it took great effort and resources to hunt them down. These three aspects of the war at sea are closely examined in this interesting study.