May 31

1916: World War I: Battle of Jutland: The British Grand Fleet under the command of John Jellicoe, 1st Earl Jellicoe and David Beatty, 1st Earl Beatty engage the Imperial German Navy under the command of Reinhard Scheer and Franz von Hipper in the largest naval battle of the war, which proves indecisive.

1942: World War II: Imperial Japanese Navy midget submarines begin a series of attacks on Sydney, Australia.