Who won the second battle of Bull Run?

On July 21, McDowell's Army of Northeast Virginia executed a complex turning movement against Beauregard's Confederate Army of the Potomac, beginning the First Battle of Bull Run (also known as First Manassas). Although the Union troops enjoyed an early advantage, driving the Confederates back, the tide turned that afternoon. Col. Thomas J. Jackson inspired his Virginia brigade to withstand a strong Union attack and he received his famous nickname, "Stonewall" Jackson. Timely reinforcements arrived by railroad from Johnston's army; Patterson had been ineffective in keeping them occupied. The green Union soldiers began to fall back and it turned into a panicky retreat, with many running almost as far as Washington. Civilian and political observers, some of whom had treated the battle as festive entertainment, were caught up in the panic. The army returned safely to Washington; Beauregard's army was too tired and inexperienced to launch a pursuit. The Union defeat at First Bull Run shocked the North and a new sense of grim determination swept the United States as military and civilians alike realized that they would need to invest significant money and manpower to win a protracted, bloody war.