The day after storming Marye's Heights, Sedgwick's victorious corps was surrounded on three sides by Lee's forces and forced to retreat back across the Rappahannock.
The Battle of Salem Church (May 3–4, 1863) was the immediate sequel to Sedgwick's capture of Marye's Heights. Fresh from that victory, Sedgwick's 23,000-man VI Corps marched west along the Orange Plank Road toward Chancellorsville to relieve Hooker — only to find Lee had already sent forces to block them.
Confederate General Lafayette McLaws rushed his division to Salem Church, arriving just in time to form a line as Sedgwick's advance approached. Sedgwick initially thought he faced only a small blocking force and attacked with a single division — a costly underestimation that was repulsed before sunset.
On May 4, Lee orchestrated a three-sided squeeze: Early attacked from the east after recapturing Marye's Heights, McLaws pressed from the west, and Anderson threatened from the south. Sedgwick's 20,000 men held a six-mile defensive line against 25,000 Confederates with no help coming.
Hooker refused to launch a coordinating attack from Chancellorsville to relieve the pressure, leaving Sedgwick to fight alone. Confederate assaults were repeatedly repulsed throughout the day, but Sedgwick's position was simply untenable — outnumbered and surrounded on three sides with a river at his back.
After dark on May 4, Sedgwick withdrew his corps across the Rappahannock at Banks' Ford in good order, completing the crossing by 4 a.m. on May 5. When Hooker learned the VI Corps had retreated, he abandoned the entire Chancellorsville campaign and pulled the whole Army of the Potomac back across the river.
Salem Church is one of the Civil War's forgotten battles — overshadowed by Chancellorsville — yet its outcome was decisive. Sedgwick's failure to break through and link up with Hooker sealed the Union defeat, turning Lee's tactical brilliance at Chancellorsville into a complete strategic victory.