Watch Online Free on Watchseries. After giving a brief overview of the events leading up to the United States Civil War, this video uses historical photos and reenactments to explore the first major land battle of the American Civil War at Manassas, Virginia. The July 21, 1861 battle, known both as Manassas and the First Battle of Bull Run, is shown in a step-by-step process detailing various troop movements throughout the day.