Zane's furnace and forge was the largest operation of its kind in the Valley. As he added to his holdings, a small community developed within close range of the iron works. At times Zane employed more than 100 men and he owned a dozen or so slaves. By 1772 the iron works produced tons of stoves, pots and bar iron using a two-hammer forge and ten-foot-square furnace. "The products of this industry were hauled by wagon to Alexandria on the Potomac and Falmouth on the Rappahannock, where they were shipped to Bristol, London, Glasgow, or Boston."

During the Revolutionary War, Zane's Marlboro Iron Works became a munitions factory producing four- and six-pound ordnance, shot, langrage, swivel balls, and chain shot.- US NRHP Registration Form