Naval operations 48 Submarine 48 World War, 1939-1945 45 History 16 Naval operations, American 11 Campaigns 9 Naval operations, German 9 World War 8 Biography 7 World War, 1914-1918 6 Submarine warfare 5 World war, 1939-1945 5 Naval operations, British 4 Naval Operations 3 Naval operation 3 Pacific Ocean 3 Submarines 3 World War,1939-1945 3 Anti-submarine warfare 2 Atlantic Ocean 2 Germany 2 Naval operations, Japanese 2 Naval operations,German 2 Personal narratives 2 Sailfish (Submarine) 2 Submarine boat captains 2 Warships 2 20th century 1 Admirals 1 Aerial operations 1