When war broke out, John Chapman's mill served the Confederate Subsistence Department as a meat-curing and distribution center. On March 9, 1862, Confederate Gen. Joseph E. Johnston ordered the stockpiles there destroyed during the evacuation of northern Virginia so they would not fall into Union hands, and two million pounds of meat burned. The destruction soon was overshadowed by the fierce fighting for Thoroughfare Gap on August 28, 1862, when the mill changed hands three times. The 9th Georgia and 13th Massachusetts Infantry fought for control of the mill as soldiers crawled over rocks, through ravines, and into quarries to gain advantage. When the 11th Pennsylvania Infantry charged past the site, fire from the buildings and the heights above cut them to pieces. By the end of the day, Confederate Gen. James Longstreet's men had forced Union Gen. James B. Rickett's smaller force out of the gap, enabling Longstreet to link up with Gen Thomas J. "Stonewall" Jackson's corps and contributing to another Union defeat at the Second Battle of Manassas two days later. The mill's destruction ruined John Chapman economically, physically, and emotionally, and he suffered a mental breakdown. Though left windowless, floorless, and deserted, the mill continued to draw partisan raids, skirmishes, and pickets. In 1864, Chapman's family committed him to Western Lunatic Asylum, where he died two years later. Jonathan Chapman and his son Nathaniel built the mill between 1737 and 1742. Its location between the Shenandoah Valley and the ports of Georgetown and Alexandria was ideal, and after the Manassas Gap Railroad was built in the 1850s, John Chapman expanded it from three to seven stories, making it the tallest stack-stoned building in the country. The Beverly family restored the mill by 1878, and it remained in operation under successive owners until 1951. An arson fire in 1998 again reduced it to ruins, and preservation efforts continue.
