Smith's home state of Kentucky became a
border state when the American Civil War began in 1861. Some months afterward, Smith presented himself in
Richmond, Virginia, to serve in the
Confederate States Army. Commissioned as a
major general on September 19, he served in
Northern Virginia as a divisional and "wing" commander. He fought in the
Battle of Seven Pines near Richmond during the
Peninsula Campaign. On May 31, 1862, because he was the senior major general in the
Army of Northern Virginia, Smith briefly took command after Gen.
Joseph E. Johnston was wounded at Seven Pines. However, Smith's nerve broke, and
Jefferson Davis replaced him with
Robert E. Lee the following day, June 1. On June 2, Smith took a leave of absence to recuperate. In late August, Smith returned and took command of the defenses around Richmond, which was expanded to become the Department of North Carolina & Southern Virginia in September. In addition, he acted as interim
Confederate States Secretary of War from November 17 through November 21, 1862. Smith resigned his commission as a major general on February 17, 1863, and became a volunteer aide to General
P. G. T. Beauregard for the rest of that year. Smith was also the superintendent of the
Etowah Iron Works from 1863 until June 1, 1864, when he was commissioned a major general in the
Georgia Militia, commanding its first division until the war's end. ==Postbellum life and death==