Gustavus Woodson Smith was born to Byrd Smith (12 May 1790-13 February 1872) and Sarah Hatcher Woodson (22 January 1796-05 November 1867) on 30 November 1821 in Georgetown, Scott County, Kentucky. He graduated eighth in his class from United States Military Academy in West Point, Orange County, New York in 1842. Assigned to the U.S. Army Corps of Engineers, he became involved in the construction of coastal fortifications. During this period, he met Lucretia Bassett (19 May 1822-04 February 1881) of New London, New London County, Connecticut and they were married on 03 October 1844.

     He worked the next two years as Assistant Professor of Engineering at West Point. In the Mexican War (1846-1848), he was charged with the leadership of a company of miners, sappers and pontoniers. He was brevetted to Captain for exemplary service and gallantry in the battles of Cerro Gordo (17-18 April 1847) and Contreras (19-20 August 1847). Thereafter, he returned to West Point as Principal Assistant Professor of Engineering, until his resignation from the Army on 18 December 1854. He continued to apply his engineering skills in civilian life, directing renovation efforts on government buildings, and he also served as a street commissioner for New York City.

     Smith was commissioned a major general in the Confederate Army on 17 September 1861 and soon given command of Second Corps, Army of the Potomac (Confederate). From 23 March 1862 to 18 April 1862, he was responsible for the administration of Aquia District of Department of Northern Virginia. During the Peninsula Campaign (17 March 1862-13 August 1862), he commanded the reserves and was in charge of the rear guard of the Army's retreat toward Richmond. When Gen. Joseph Eggleston Johnston (03 February 1807-21 March 1891) was wounded in the Battle of Seven Pines (31 May 1862-01 June 1862), he temporarily assumed command of the Army, until Gen. Robert Edward Lee (19 January 1807-12 October 1870) relieved him the following day. He was later assigned command of the defenses of Richmond on 30 August 1862, which was expanded and designated Department of North Carolina and Southern Virginia on 19 September 1862.

     When George Wythe Randolph (10 March 1818-03 April 1867) resigned, he briefly served as Secretary of War (Ad Interim) (17 November 1862-21 November 1862), until James Alexander Seddon (13 July 1815-19 August 1880) took office. He resigned his commission on 07 February 1863, but was later appointed Major General in the Georgia Militia and actively organized conscription efforts in that state. He served admirably in defense of Military District of Georgia (and Third Military District of South Carolina), particularly in the Battle of Honey Hill (30 November 1864), which briefly helped preserve the Charleston & Savannah Railroad. Smith and his troops were captured at Macon, Bibb County, Georgia on 20 April 1865.

     After the war, he was Superintendent of Southwestern Iron Works in Chattanooga, Hamilton County, Tennessee from 1866 to 1870, before serving as Insurance Commissioner of Kentucky until 1876. He then moved to New York City, and wrote books on insurance and his military experiences until he died on 24 June 1896. Smith is buried in his wife's family section of Cedar Grove Cemetery in New London, New London County, Connecticut.