From the fort, General Evans successfully orchestrated the defense of Leesburg during the Battle of Ball's Bluff.

The fort was abandoned when the Confederates withdrew from Loudoun County to defend Richmond during the Peninsula Campaign in 1862 and briefly occupied by the Union army under John Geary during his occupation of the town that same year.

In June 1863, the fort was briefly occupied during the Gettysburg campaign by the Federal XII Corps under Major General Henry Slocum.

Fort Evans guarded the approaches to Edwards Ferry, which was at the time the site of two pontoon bridges.

A number of gun embrasures for the placement of batteries were put on each wall, despite the relatively small amount of artillery assigned to the garrison at Leesburg