Army of the Potomac

noun U.S. History.
  1. Union forces, trained and organized by Gen. 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.
Dictionary.com Unabridged Based on the Random House Unabridged Dictionary, © Random House, Inc. 2018