With the regiment's original three-year enlistments expiring on June 11, 1864, those who chose not to re-enlist were sent back to Madison, with the final company mustering out on July 2, 1864. Newer recruits and re-enlisted veterans were restructured into a battalion of two companies, first under the command of Captain Dennis B. Dailey, then under Lt. Albert T. Morgan, and finally Lt. Henry Naegly. The battalion participated in the Siege of Petersburg—suffering several more casualties during that campaign—until they were ultimately consolidated into the 6th Wisconsin Infantry Regiment on November 30, 1864.