- Sep 6 1st (failed) submarine attack: David Bushnell's "Turtle" attacks British sailboat "Eagle" in Bay of NY
- Sep 6 Hurricane hits Guadeloupe, killing more than 6,000.
- Sep 6 Hurricane hits Martinique; 100 French and Dutch ships sink; 600 die
- Sep 9 Congress officially renames the country as the United States of America (from the United Colonies)
Nathan Hale Volunteers
Sep 10 George Washington asks for a spy volunteer, Nathan Hale volunteers
- Sep 12 Nathan Hale leaves Harlem Heights Camp (127th St) for spy mission
- Sep 15 British forces capture Kip's Bay, Manhattan, during Revolution
- Sep 17 The Presidio of San Francisco is founded in New Spain.
- Sep 21 5 days after British take New York, a quarter of the city burns down
- Sep 21 Nathan Hale, American rebel spy is arrested by British militia in NYC
- Sep 24 First St Leger horesrace held at Doncaster