Submarine Naval operations 43 World War, 1939-1945 33 History 11 Campaigns 8 Naval operations, German 8 Naval operations, American 7 World War 7 Submarine warfare 6 World War, 1914-1918 6 Biography 5 Naval operations, British 4 World war, 1939-1945 4 Naval Operations 3 Pacific Ocean 3 World War,1939-1945 3 Naval operation 2 Naval operations, Japanese 2 Naval operations,German 2 Naval warfare 2 Navaloperations 2 Personal narratives 2 Submarine boat captains 2 World War, 1939 - 1945 2 20th century 1 Admirals 1 Anti-submarine warfare 1 Antisubmarine Warfare 1 Atlantic Ocean 1 Case studies 1