The 6th Wisconsin was raised at Madison, Wisconsin, and mustered into Federal service July 16, 1861 for a term of three years. It saw severe fighting in the 1862 Northern Virginia Campaign, fighting at Brawner's Farm during the early part of the Second Battle of Bull Run. During the subsequent Maryland Campaign, the 6th attacked Turner's Gap in the Battle of South Mountain, and then suffered considerable casualties battling Hood's Texas Brigade in the D.R. Miller cornfield at Antietam.
During the first day of the Battle of Gettysburg on July 1, 1863, Lt. Col. Rufus R. Dawes led a counterattack on Joseph R. Davis's Confederate brigade of Mississippians, many of which were sheltered in an unfinished railroad cut west of town. The 6th forced the surrender of over 200 enemy soldiers. The regiment later served that year in the Bristoe and Mine Run Campaigns.
The regiment participated in the Grand Review of the Armies on May 23, 1865, and then mustered out at Louisville, Kentucky on July 2, 1865. The 6th Wisconsin Infantry initially mustered 1029 men and later recruited an additional 601 men, for a total of 1,630 men. The regiment lost 16 officers and 228 enlisted men killed in action or who later died of their wounds, plus another 1 officer and 112 enlisted men who died of disease, for a total of 357 fatalities