Born in Missouri, Alonzo William Slayback was ten years old when he enrolled in the Masonic College in Lexington, Missouri. After graduating, Slayback taught school and studied the law, opening a law practice in 1857 in St. Joseph, Missouri. In June 1861, Slayback raised a cavalry regiment and joined the Missouri State Guard command of Maj. Gen. Sterling Price. After the expiration of his term of service, Slayback raised another regiment for service in the Confederate States Army. At the end of the war, Slayback, along with 48 from his regiment, accompanied Brig. Gen. Jo Shelby into exile in Mexico. After a year, Slayback returned to St. Louis in 1866 and returned to the practice of law.
Reavis, “Colonel A. W. Slayback.” In Saint Louis: The Future Great City of the World, 489–92.