Shows the Potomac River in the area of Loudoun County, Va., and Montgomery County, Md., where Union troops under Col. Edward D. Baker faced Confederate troops commanded by Evans. What was meant to be a "a slight demonstration" against the Confederate forces guarding the fords quickly became a rout. Col. Baker was one of the casualties.
The map shows the location of troops on either side of the Monocacy River and north into the city of Frederick, Md. This engagement, part of "Early's Washington Raid" took place on July 9, 1864. Early's troops met Federal forces near the river. The Union troops were routed and retreated to Baltimore.