With business booming by 1855, Colt entered an aggressive expansionary phase and opened the Colt Armory, the world's largest private armament factory. He employed advanced manufacturing techniques such as interchangeable parts and an organized production line. By 1856, the company could produce 150 weapons per day. The Civil War led to a surge in demand, and Colt supplied the Union Army. Colt's Patent Fire-Arms Manufacturing Company operated at full capacity and employed over 1,000 people in its Hartford factory. By that time, Colt had become one of the wealthiest men in America. He was presiding over his enterprise from Armsmear, an ornate Italianate manor built near the armory in 1857. Upon his death in 1862, he was worth over $15 million ($380 million by 2015 standards).