Major General Francis H. Smith was the first Superintendent, 1839–1889, and first part-time Commandant (VMI commandants were part-time until 1907) of the new Virginia Military Institute VMI. Thomas Jonathan Jackson, a US Military Academy Graduate, later to become well known by his nickname of Stonewall Jackson, joined the VMI faculty in 1851. Jackson's intimate knowledge of this and other crossings of the Blue Ridge facilitated his tactics, and enabled him to intimidate Union leaders such as General George B. McClellan into being less aggressive with their own plans of advancement in the first years of the American Civil War (1861–1865). Jackson and his famous "foot cavalry" used Swift Run Gap (among others) to shift his troops rapidly from the Shenandoah Valley theater to the Piedmont, which allowed him to appear unexpectedly before Union forces on several occasions.