- Sep 1 Grant assumes command of Federal forces at Cape Girardeau MI
- Sep 1 Skirmishes at Boone Court House WV & Blue Creek WV
- Sep 3 Confederate forces enter Kentucky, thus ending its neutrality
Historic Event
Sep 6 General Ulysses S. Grant occupies Paducah, Kentucky
- Sep 9 Nurse Sally Tompkins is officially commissioned as an officer (and its only woman officer) by the Confederate US Army
- Sep 10 -15] Battle at Cheat Mountain, Elkwater, West Virginia
- Sep 10 Battle of Carnifex Ferry in Virginia, 170 casualties
- Sep 13 1st naval battle of Civil War, Union frigate "Colorado" sinks privateer "Judah" off Pensacola, Fla
- Sep 16 Battle of Princeton, West Virginia
- Sep 16 British Post Office Savings Banks opens
- Sep 17 First class for escaped slaves taught by Mary Peake at Fortress Monroe Virginia (now Hampton University).
- Sep 20 Battle of Lexington, MI-captured by Union
- Sep 22 Fort Fauntleroy (Wingate) in New Mexico fires on and kills Navajo Indians after horse race dispute
- Sep 25 Secretary of US Navy authorizes enlistment of slaves
- Sep 26 British Open Men's Golf, Prestwick GC: Tom Morris Sr. beats Willie Park Sr. by 4 strokes