Cyrus E. Briant enlisted as a captain in the 88th Indiana Infantry in August 1862, was promoted to lieutenant colonel in December 1862, and was commissioned (but never mustered) colonel in October 1863. The regiment served in the Army of the Cumberland through the Chickamauga, Chattanooga, and Atlanta campaigns and the March to the Sea. Briant received a brevet colonelcy in March 1865 and mustered out that June at Washington, D.C.