In May 1862, Mower was elected colonel of the Eleventh Missouri Infantry. Within a year, he was promoted to brigadier general. He served at the battles of Iuka and Corinth. He directed a brigade during the Vicksburg campaign. During the Red River campaign, he served at Fort DeRussy and in a command position at Yellow Bayou. He served under Sherman in the Atlanta and Carolina campaigns with great distinction. He remained in the army after the end of the war.
