"At outbreak of the Civil War he was living in Philadelphia and working for the B&O Railroad. He left his position there and moved to Wheeling to take command of the 1st Virginia Infantry, a Federal volunteer three-months regiment, and was appointed as its colonel.[1][2] His first service was at Philippi, where he captured the Confederate camp equipage and was himself badly wounded. He was promoted to brigadier general of volunteers on August 5, 1861, backdated to May, and was victorious at Romney and Blue's Gap (Hanging Rocks Pass). Afterward, Kelley commanded a division of 10,000 men in the Department of Harper's Ferry.In 1862 he served under Maj. Gen. John C. Frémont, and the following year he was in command of the West Virginia department and pursued General Robert E. Lee during the Retreat from Gettysburg. In 1864, he checked the enemy at Folck's Mill, New Creek, and Moorefield, West Virginia. He was brevetted as a major general of volunteers on August 5, 1864.[3]Kelley, along with his immediate superior Maj. Gen. George Crook, was captured by a small raiding party of Confederate partisans on February 21, 1865. Kelley was sent to a prison in Richmond, Virginia, but he and Crook were released on March 20 by a special exchange. He resigned from the army on June 1, 1865.[3]