Even before Tennessee joined the Confederacy in 1861, officials examined the state’s caves for saltpeter, an essential ingredient in gunpowder. The soil at Cumberland Caverns was ideal, and saltpeter had been mined there in Henshaw Cave during the War of 1812. Nashville’s Sycamore Powder Mills, the larger of two major gunpowder mills in the South, used saltpeter, charcoal, and sulfur to make gunpowder, and Henshaw Cave soon produced saltpeter for the Confederacy. Workers leached nitrates from the cave soil with water from the cave, poured the solution into eighty-gallon cast-iron crucibles outside, added lye made by leaching water through oak and hickory charcoal or ashes, and boiled the liquid over wood fires to produce the saltpeter crystals needed for gunpowder. Saltpeter made here and at nearby caverns was transported to Nashville until the Federals occupied the city in 1862, after which it was taken to other mills. As demand increased, the price of saltpeter rose sharply, reaching $1.50 a pound in 1864 from $0.25. Postwar explorations uncovered many artifacts of this industry, including hollowed wooden water pipes, wooden paddles, leaching pits, and assorted tools.