(July 9, 1864), American Civil War engagement fought on the banks of the Monocacy River near Frederick, Md., in which Confederate troops under Lieutenant General Jubal A. Early routed Union forces under Major General Lewis Wallace. Although the Union forces were defeated, the delay caused by the battle gave General Ulysses S. Grant time to send reinforcements for the defense of Washington, D.C. Of 6,050 Federal troops in the engagement, there were 1,880 casualties. Of 14,000 Confederates involved, there were fewer than 700 casualties.