Army of the Potomac

[ ahr-mee uhv thuh puh-toh-muhk ]

noun

, U.S. History.

1. Union forces, trained and organized by General George B. McClellan, that guarded Washington, D.C., against a Confederate invasion across the Potomac and fought battles in the eastern sector during the Civil War.
2. Confederate forces from the Alexandria, Potomac, and Shenandoah districts from mid–1861 to mid–1862: later known as Army of Northern Virginia.