During the Battle of McDowell, beginning around 4:30 pm and continuing for about four hours, Union soldiers advanced doggedly uphill toward the Confederate defensive line, loading and firing as they came, while Confederate soldiers on both sides returned fire and suffered heavy casualties. The Federal assault, launched despite being heavily outmanned and attacking from an inferior position, surprised Confederate commander Gen. "Stonewall" Jackson and his troops. Union soldiers used ravines to reduce their exposure as they climbed the steep, rugged slopes, and although greatly outnumbered, the Union regiments moved steadily upward and inflicted heavy losses along the Confederate line. Their rifled muskets gave them greater accuracy and range, the setting sun silhouetted the southerners against the sky, the mountain's shadows concealed the Federals, and Confederate fire aimed downslope often passed too high. Under heavy pressure, the Confederates rushed reinforcements up the hill to stabilize the line and held their position. As darkness increased and Federal troops ran low on ammunition, Union Gen. Robert H. Milroy reluctantly ordered a withdrawal, and the Federals pulled back down the mountain to McDowell.