Attached to the XI Corps of the Army of the Potomac, it lost 155 men at Chancellorsville, including Colonel Hecker, who was badly wounded.

Although just 23 men were battlefield casualties at Gettysburg, 89 were captured during the retreat through the town.

In the fall of 1863, it moved with the rest of the XI Corps to the Western Theater.

Colonel Hecker had recovered from his wounds by now and was promoted to brigade command (he would ultimately resign the following winter).

After seeing action at Chattanooga, the 82nd Illinois became part of the new XX Corps and joined the rest of Sherman's army in the 1864-65 campaigns in Georgia and the Carolinas.