Battle of Cedar Mountain
Maj. Gen. John Pope was appointed to command the newly-formed Army of Virginia on June 26th. His orders were to defend Washington DC and the Union-held areas of northern Virginia while the Army of the Potomac, led by Maj. Gen. George B. McClellan, engaged Robert E. Lee outside Richmond. Following McClellan’s defeat at the end of the Seven Days Battles less than a week later, Lee shifted his focus northward towards Pope, as McClellan regrouped his forces. Pope’s three army corps were positioned in a line stretching from the Blue Ridge Mountains to the Rappahannock River. Lee countered by sending Maj. Gen. Thomas J. “Stonewall” Jackson with 14,000 men to Gordonsville, targeting the center of Pope’s line. Jackson was later reinforced by Maj. Gen. A.P. Hill’s division. On August 6th, Pope advanced his forces south into Culpeper County with the goal of capturing the rail junction at Gordonsville. On August 9th, Jackson and Maj. Gen. Nathaniel Banks’s Second Corps of Pope’s army clashed at Cedar Mountain, with the Federals initially gaining the upper hand. However, a Confederate counterattack led by Hill on the Union right repulsed the Federals and secured a Confederate victory. During the battle, Confederate Brig. Gen. Charles Winder was killed. The engagement at Cedar Mountain shifted the focus of fighting in Virginia from the Peninsula to Northern Virginia, granting Lee the strategic initiative.
Reference: https://www.battlefields.org/learn/civil-war/battles/cedar-mountain