General William Tecumseh Sherman replaces General Robert Anderson as commander of the Department of the Cumberland. Anderson had suffered a severe mental breakdown.
Braxton Bragg [CS] and Don Carlos Buell [US] fight the largest battle on Kentucky soil. The battle is generally regarded as a draw, although Buell claimed victory. Less than half of Buell's men participated because he did not know a major battle was taking place less than 2 miles from his headquarters