In June 1864, Union Lieutenant General Ulysses S. Grant sought to destroy Confederate General Robert E. Lee's army at Petersburg, Virginia, while Lee saw an opportunity to capture undefended Washington, D.C. and sent Lieutenant General Jubal A. Early with 15,000 troops to invade the North. Moving through the Shenandoah Valley to Frederick, Maryland, Early expected only minor resistance but instead encountered 6,000 opposing troops. Although his army won the Battle of Monocacy on July 9, 1864, the delay cost him his chance to take Washington and perhaps to turn the war in favor of the Confederacy. In the 1864 Valley Campaign, Early departed Richmond on June 13, secured the Shenandoah Valley, moved into Maryland, fought Union troops reinforced by Grant at Monocacy on July 9, advanced on Washington's defenses, reached Fort Stevens on July 11, and retreated into Virginia on July 12 when he found the odds too great. Best Farm came under artillery crossfire at the battle's opening, Confederates forded the Monocacy River at Worthington Farm and shifted the fighting to a new front, civilians hid in Thomas House during fierce combat, Gambrill Mill served as a Union field hospital, and defending Monocacy Junction was central to Union strategy. James H. Gambrill had purchased the mill in 1855, and after the war he operated it until 1897.
