F ederal troops came into Rockville in the June of 1861, when the war had just begun. From June 1-7 1861, troops came to Rockville during the Rockville Expedition, in a search for pro-Confederates. Many regiments stopped in Rockville as they came through the county.

In September 1862, the center wing of George McClellan's army stayed briefly in Rockville on the way to Frederick, South Mountain, and Antietam. From the 7th to the 11th, McClellan's troops made their headquarters on Falls Road. On June 28 of the following year, Jeb Stewart's cavalry came in from northern Viginia. One brigade came down Darnestown Road, the other down Falls. It being a rebel cavalry, they were cheered on as they passed through. One girls' seminary, located on the corner of Washington Street and Commerce Lane (now West Montgomery Avenue), sang for the troops as they came by. Pro-Unioners hid; some were captured.

The most memorable visit to Rockville was made by Jubal Early.