President Abraham Lincoln signs the executive order emancipating all slaves in states and parts of states controlled by the Confederacy.
A major battle begins near Murfreesboro, Tennessee, when Braxton Bragg’s Confederate Army of Tennessee attacks the Federal army under William S. Rosecrans.
Ambrose Burnside launches a doomed Federal assault on Robert E. Lee’s Confederate defenses south and west of Fredericksburg.
The bloodiest day in American history takes place as the armies of Robert E. Lee and George B. McClellan fight to a standoff near Sharpsburg, Maryland, along Antietam Creek.
Letter from David Ash, Company B, 37th Illinois Volunteer Infantry, three days after the Battle of Pea Ridge.
Henry H. Sibley’s Confederate Army of New Mexico begins its mission to conquer the New Mexico Territory, culminating in a fight for a ford on the Rio Grande.