At the outbreak of the war, Butler resigned from the South Carolina state legislature to become a captain in the Edgefield volunteers. He served at the Battle of First Manassas as captain of the Hampton Legion. Subsequently, he was promoted to captain. In May 1862, he served at the Battle of Williamsburg. He received the position of colonel of the 2nd South Carolina Cavalry, which he led in the Battle of First Manassas, the battle of South Mountain, and the battle of Antietam. In June 1863, he lost his right foot at the Battle of Brandy Station. He returned to service in September with a promotion to brigadier general. Due to his excellent performance in the battles of the Wilderness and Spotsylvania Court House, he received another promotion to major general of cavalry. He participated in the battles of Haw's Shop, Cold Harbor and Trevilian Station before he was sent to the Carolinas to try to stop the advance of the Union forces from the South. He was forced to surrender his command in April 1865.
