Established as a tavern in 1744, the Elkridge Furnace Inn stood beside a furnace complex that by 1860 included over a dozen buildings owned by the Great Falls Iron Company. In 1810, the Ellicott brothers purchased the furnace and tavern and attached an elegant dwelling to the inn for their families. On May 5, 1861, the 8th New York and 6th Massachusetts Infantry Regiments and Cook's Boston Battery of light artillery occupied the surrounding heights to prevent Confederate sympathizers from sabotaging the Thomas Viaduct, the only rail link to Washington, D.C., from the north and the most important and vulnerable target for saboteurs in central Maryland. Other U.S. Army regiments and batteries later occupied fortifications on both sides of the river and remained in the area until the end of the war. After the war, Judge George Dobbin donated land for the Lawyer's Hill Assembly Hall near the former Union camp, envisioning the hall, built about 1870, as a neighborhood parlor where divisions caused by the war might be healed. The hall soon became the favored location for social and cultural activities formerly held in homes on the hill before the war. The furnace continued production through the Civil War before floods destroyed it in 1868 and 1873.