Regional view shows paths taken by different segments of the Union army on a march from Frederick, Md., to Gettysburg, Pa., as well as the location of the Confederate army units in the vicinity. The Union troops were under the commands of Reynolds, Howard, Sickles, Slocum, Hancock, Sykes and Gregg.
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.