The fort saw action on July 10–12, 1864, when Robert E. Lee sent 22,000 Confederates led by General Jubal A. Early against the 9,000 Union troops defending Washington (Ulysses S. Grant had depleted the Union defenses for his siege of Petersburg). The Confederates attacked from the north in Maryland. The initial warnings came from Fort Reno lookouts spying movement by Rockville. The attack itself was directed about 4 miles to the east across Rock Creek at Fort Stevens. The battle is known as "The Battle of Fort Stevens", and resulted in a Union victory.