German submarines significantly changed the strategy of warfare at sea during the First World War. For the first time in naval history, the German command began to use submarines to conduct operations in territories remote from their bases and ports. At the same time, with the development of combat submarines, anti-submarine measures began to improve, and, consequently, the defensive forces of states. The book by English naval historians R. Gibson and M. Prendergast, written on the basis of many sources that appeared immediately after the World War, contains rich factual material covering in detail the course of operations of German submarines that took place during the First World War of 1914–1918.