|Abstract||The Vicksburg campaign marked a key transitional phase of Union policy toward white Southern civilians. Initially, Northern military commanders instituted a conciliatorily approach to Southern civilians and property, but by late 1862 this policy had evolved to a pragmatic form of warfare that allowed stricter measures but still attempted to limit the physical and monetary damage inflicted upon civilians. In the Mississippi River Valley in early 1863, Major General Ulysses S. Grant's Army of the Tennessee perfected a punitive policy concerning civilians known to historians as "hard war," which authorized the destruction of all Confederate economic and transportation resources. This dissertation examines the creation of hard war policy by the lower ranks of the Union army and concludes that the Army of the Tennessee developed hard war before other Union armies due to to its deeper penetration of the Lower South. The campaign against Vicksburg transformed the way in which the war impacted the civilian population of the South. The drastic amount of damage inflicted upon the population and infrastructure by Grant's decision to forage intensely and deprive opposing armies of sustenance effectively removed this area from the conflict and created the means that would enable the Union to win the war in the next two years. The Vicksburg campaign cemented the transition from pragmatic to hard war in the western theater, from which it would later spread throughout the Confederacy in 1864.