1917    World War I: Germany announces its U-boats will engage in unrestricted submarine warfare.

1939    World War II: A German U-boat ''U 29'' sinks the British aircraft carrier {{HMS|Courageous|50|6}}.

1941    World War II: The destroyer USS ''Reuben James'' is torpedoed by a German U-boat near Iceland, killing more than 100 United States Navy sailors. It is the first U.S. Navy vessel sunk by enemy action in WWII.

1946    World War II: Operation Deadlight ends after scuttling 121 of 154 captured U-boats.

1954    The German U-Boat U-505 begins its move from a specially constructed dock to its final site at Chicago's Museum of Science and Industry.