Lewis Hanback was born on March 27, 1839, in Winchester, Illinois, to William and Ann Hanback. His father was a farmer who owned $800 of real estate in 1850. The family lived in Ellington, Illinois, and Hanback attended school there before beginning work as a teacher.
He enlisted in the Union army on August 20, 1861, and mustered in as a sergeant in Company I of the 27th Illinois Infantry on November 28, 1861. According to his service records, he was 5 feet, 8 inches tall, with dark hair and blue eyes. The regiment took part in the siege of Corinth and the Battles of Stones River, Chickamauga, Missionary Ridge, and Kennesaw Mountain. Hanback was eventually promoted to 2nd lieutenant, and he mustered out on September 20, 1864.
Hanback married Hester Cooper around 1865, and they had at least three children: Clara, born around 1866; Edwin, born around 1868; and Grace, born around 1870. The family moved to Kansas around 1866, and Hanback worked as a lawyer there. He was elected Justice of the Peace in 1867 and served as Probate judge for Shawnee County from 1868-1872. He became assistant secretary of the state senate in 1877 and spent two years as assistant US district attorney for Kansas. He served as a Republican Congressman from 1883 to 1887. He joined the local chapter of the Grand Army of the Republic in 1893, and he died in Kansas City on September 7, 1897.