Columbus L. Harris enlisted in Co. M, 4th Arkansas Cavalry, U.S. Volunteers, at Pine Bluff, Arkansas, on October 3, 1864, for three years. He died in a military hospital at DeValls Bluff, Arkansas, on January 22, 1865, and is interred in Little Rock National Cemetery. The descriptive roll states that when enlisted he was a farmer, age 18, born in Monroe County, Mississippi, eyes blue, hair dark, complexion fair, height 5'10".

This ties in all the Harris boys listed in the 1850 census of Monroe County, Mississippi, to Jefferson County, Arkansas (or more accurately, that part of Jefferson County that became part of Cleveland County).