He served as a Union Army officer during the American Civil War and was then elected as a reconstruction-era U.S. congressman from Alabama.

Born in Fayetteville, North Carolina, Callis moved to Tennessee in 1834 with his parents, who settled in Carroll County, and thence, in 1840, to Lancaster, Wisconsin Territory.

Due to the high casualty rate among its officers, Callis led the regiment at the Battle of South Mountain, Antietam, and several other engagements.

After a lengthy recovery, he rejoined the Army and was appointed by President Abraham Lincoln military superintendent of the War Department at Washington, D.C., in 1864.

He was promoted to lieutenant colonel February 11, 1865, and was subsequently granted a double brevet to brigadier general of volunteers.

Upon the readmission of the State of Alabama to representation Callis was elected as a Republican to the Fortieth Congress and served from July 21, 1868, to March 3, 1869.

He was elected to a single one-year term in the Wisconsin State Assembly in 1874 as part of the short-lived Liberal Reform Party.