After working for American Express, co-founded by his father, Butterfield served in the Civil War, where he was soon promoted brigadier general, and wounded at Gaines' Mill. While recuperating, he either wrote or re-wrote a popular bugle-call for burials, called "Taps". He commanded a division at Fredericksburg, and then became Hooker's chief of staff, sharing both the credit for improved morale and responsibility for the licentious behaviour that Hooker tolerated in camp. He also became embroiled in Hooker’s political feuds with Burnside and Meade. Wounded at Gettysburg, he served in Sherman’s Atlanta campaign, before retiring from front-line service through illness. He later received the Medal of Honor.