The Battle of Gunpowder River was a fictional alternate history battle fought between the Confederate States of America and the United States on July 21 1863 not far from Gunpowder River, Maryland during the American Civil War. It is depicted in the book Grant Comes East. The end result of the Battle of Gunpowder River was another stunning victory for the Confederates. With the Army of the Potomac officially finished as an effective fighting force, U.S. Grant was forced to begin the the final campaign of the war with only his own army available to face Robert E. Lee.