BENTON COUNTY, AR—Union Brigadier General Samuel R. Curtis leads an outnumbered Union army to victory at the Battle of Pea Ridge. This victory ended the Confederate threat to Missouri and Federal soldiers secured northern Arkansas.
NEW YORK, NY—The USS Monitor leaves New York Harbor, accompanied by the USS Currituck and USS Sachem, headed for Hampton Roads, Virginia.
COLUMBUS, KY—Confederate General Leonidas Polk leaves Columbus, ending the Confederate defensive line of Kentucky. Polk initially violated Kentucky's neutrality by occupying Kentucky in September 1861.