This hymn was inspired by an incident at the Battle of Allatoona in the American Civil War. A Union garrison under Brig. Gen. John M. Corse was under heavy attack from a Confederate division led by Maj. Gen. Samuel G. French. The garrison was very close to defeat, when they received a flag-signal from Maj. Gen. William T. Sherman saying "Sherman is moving in force. Hold out," and then, "General Sherman says hold fast. We are coming." The Union garrison, encouraged by Sherman's message, were able to hold out until reinforcements arrived.