Howry was born on May 14, 1844 in Oxford, Mississippi, the son of James M. Howry and Narcissa (Bowen) Howry. He received his early education in Oxford and began studies at the University of Mississippi, but left college to serve in the American Civil War. Howry joined the Confederate States Army's 29th Mississippi Infantry Regiment as a private. He later received a commission, and attained the rank of captain. Howry's combat experience included the Battles of Chickamauga, Lookout Mountain, Missionary Ridge, Resaca, New Hope Church, Peachtree Creek, Atlanta, Jonesborough, and Franklin. Howry was wounded at the Battle of Franklin, and remained in the military until the end of the war. After the war, Howry was a longtime member of the United Confederate Veterans. He served in several leadership roles, including commander of the Army of Northern Virginia department with the rank of lieutenant general.