This Day in History: 0000-09-17

17 Sep – Swedish and Saxon forces under the command of Gustavus Adolphus (1594-1632) crushed forces of the Holy Roman Empire, Hungary and Croatia in the Battle of Breitenfeld, a major Protestant victory in the Thirty Years’ War (1631).
17 Sep – Army of the Potomac under General George McClellan and Army of Northern Virginia under Robert E. Lee fought to a draw in the bloodiest day in US history at Antietam (1862).