Early in the U.S. Civil War, Mason's Hill was strategically important because of its high elevation and commanding views of nearby roads, including Columbia Turnpike and Little River Turnpike, and along with Munson's Hill and Bailey's Crossroads it became especially significant. Soon after the First Battle of Manassas on July 21, 1861, Confederate Col. J.E.B. Stuart and his men occupied Munson's Hill and remained there until September 21, making it the closest Confederate position to Washington, D.C., where President Abraham Lincoln could see a Confederate flag from the White House. Stuart's men built log imitation cannons called Quaker Cannons to mislead the Union Army about Confederate artillery strength, the first use of this tactic in the war. Stuart also maintained an outpost at Mason's Hill, where Col. Edward P. Alexander built a signal corps observation tower with a six-foot astronomical glass to watch Washington, and Confederate spy E. Pliny Bryan planned to signal messages from his Washington rooming-house window before the Confederates withdrew and the Union occupied the area. In nearby fields between Munson's Hill and Bailey's Crossroads, Union Gen. George B. McClellan held a military review on Nov. 20, 1861, attended by Lincoln, his cabinet, and thousands of spectators, to raise the morale of an army demoralized by defeat at Manassas and to display the 65,000 well-trained and well-equipped soldiers he had shaped into the Army of the Potomac.
