On November 7, 1862, the 1st Missouri Infantry and the 4th Missouri Infantry were combined into a single unit. The consolidation occurred because both units had suffered heavy losses. Because Archibald MacFarlane, the colonel of the 4th Missouri, had been severely wounded at the Second Battle of Corinth and was unfit for further service, Amos Camden Riley, colonel of the 1st Missouri, commanded the regiment. Hugh A. Garland served as the regiment's major; the regiment did not have a lieutenant colonel until Garland was promoted to that rank on May 1, 1863. The regiment's company organization as of November 7, 1862, was: