- 1752 Britain and the British Empire (including the American colonies) adopt the Gregorian Calendar (no Sept 3 - Sept 13)
- 1812 Napoleon occupies Moscow and the fires start, extinguished by the 19th
- 1939 World’s 1st practical helicopter, the VS-300 designed by Igor Sikorsky takes (tethered) flight in Stratford, Connecticut
- 1949 India's Constituent Assembly adopts Hindi as an official language. Celebrated today as Hindi Day.
- 1956 1st prefrontal lobotomy performed in Washington, D.C.
- 1960 Iraq, Iran, Kuwait, Saudi-Arabia and Venezuela form the Organization of Petroleum Exporting Countries (OPEC)
Francis Scott Key pens the poem "Defence of Fort M'Henry", later known as "The Star-Spangled Banner" while witnessing the bombardment of Fort McHenry from a ship in Baltimore harbor
On September 14, 1814
- 1830 Princess WFLC Marianne marries Albrecht of Prussia
- 1835 American leading transcendentalist Ralph Waldo Emerson (33) marries 2nd wife Lydia (Lidian) Jackson in Plymouth, Massachusetts.
- 1838 Newly escaped slave Frederick Douglass marries free woman Anne Murray in New York
- 1886 Neurologist Sigmund Freud (30) weds Martha Bernays (25) in Hamburg, Germany
- 1892 AP Giannini marries Clorinda Cuneo