CAVERNS OF WAR: CONFEDERATE SALTPETER CAVE OPERATIONS IN WESTERN VIRGINIA

Among Virginia's most important contributions of strategic materials to the Confederacy during the Civil War was niter (saltpeter), which then constituted about 75 per cent of gunpowder. Most of America's saltpeter caves are located in the Southeast because of the specific geologic, climatic, and vegetative conditions required to produce these nitrate-rich deposits. The Confederate government utilized its abundant cave deposits and other sources of niter to create a steady supply of this crucial material throughout the conflict. Niter production from caverns involved extraction of the "peter dirt," leaching with water, and treatment with potassium salts obtained typically from wood ashes. Boiling and evaporation of the leachate produced potassium nitrate (niter), which was shipped to powder mills for manufacture into explosives. The Confederacy was divided into 14 niter and mining districts, and several of these were located in the Valley and Ridge of western Virginia. At least 25 Virginia saltpeter caves were active over the course of the war, and operations at a number of these are described. The Old Dominion eventually provided more niter than any other southern state; its five niter districts produced nearly 30 per cent of the domestic supply.