These companies were raised under an order from the Secretary of War, April 9, 1862, to Major John J. McMahon.

McMahon was rewarded by being made Colonel of the 63rd in May, when the regiment was formally organized at Abingdon in Washington County, Virginia.

The 63rd ended the war with Captain (later Lieutenant Colonel) Connally H. Lynch in command.

The 63rd saw action in ten states, and by the time of its surrender on April 26, 1865, at Durham Station, North Carolina, it had fought in over 70 engagements, including the Kanawha Valley Campaign of 1862, Chickamauga, Missionary Ridge, Chattanooga, Ringold Gap, Resaca, Peachtree Creek, New Hope Church, Kennesaw Mountain, Franklin, and Stones River, among others.

After it became a part of the Army of Tennessee, the 63rd served under, at different times, James Longstreet, Patrick Cleburne, Nathan Bedford Forrest, William J. Hardee, Stephen D. Lee, and Daniel Harvey Hill.