Historical Events on September 17

21 significant historical events occurred on September 17. September 17 has been the date of several key military and political events throughout history. On this day in 1809, the Treaty of Fredrikshamn was signed, ending the Finnish War between Russia and Sweden. In 1862, the Battle of Antietam occurred during the American Civil War. During World War II in 1943, the Allies invaded Italy on this date. Other notable events include the 1894 Battle of the Yalu River and the 1961 West German federal election.