The 1st and 4th Missouri Infantry (Consolidated), which contained many men from the 1st, was assigned to the First Missouri Brigade. The new regiment was engaged in several battles in the 1863 Vicksburg campaign, including the Battle of Champion Hill. In 1864, the regiment fought at the battles of New Hope Church and Kennesaw Mountain in the Atlanta campaign, and saw further action at the Battle of Allatoona. After suffering heavy casualties at the Battle of Franklin, the regiment was transferred to Mobile, Alabama, where it surrendered at the Battle of Fort Blakely on April 9.