Naval action in World War I conjures up images of enormous dreadnoughts slugging it out in vast oceans. Yet the truth is that more sailors were killed serving on gunboats and monitors operating far from the naval epicentre of the war than were ever killed at Jutland. Gunboat engagements during this war were bloody and hard fought, if small in scale. Austrian gunboats on the Danube fired the first shots of the war, whilst German, British and Belgian gunboats fought one of the strangest, most intriguing naval campaigns in history in far-flung Lake Tanganyika. From the Mediterranean to the Black Sea, from the Balkans to Mesopotamia, gunboats played an influential part in the story of World War I. This detailed technical guide to the gunboats of all the major navies of the war means that, for the first time, the story can be told.