In June 1864, with Union Lieutenant General Ulysses S. Grant intent on destroying Confederate General Robert E. Lee's army, Lee developed a bold plan to capture Washington, D.C. He sent Lieutenant General Jubal A. Early with 15,000 troops to invade the North. Pushing through the Shenandoah Valley to Frederick, Maryland, Early expected to encounter minor resistance, but instead he found an opposing force of 6,600 troops he had not anticipated. Although his army prevailed at the Battle of Monocacy on July 9, 1864, the delay cost Early his chance to take Washington and, perhaps, to turn the war in favor of the Confederacy.
I therefore decided...to turn down the valley...to threaten Washington and if I find an opportunity—to take it.
Confederate Lieutenant General Jubal A. Early