Despite the strength of Malvern Hill, as demonstrated in the battle, McClellan felt he needed to continue with his planned withdrawal to Harrison's Landing, to Fitz John Porter's chagrin.
Porter felt the Army of the Potomac should remain atop the hill or perhaps even continue their advance to Richmond.
McClellan however insisted that Confederate troops greatly outnumbered his own, felt he could not protect Harrison's Landing from his current position at Malvern Hill, and feared being cut off from his supply depot.
McClellan's mentality prevailed.
The Union batteries and McClellan's engineers began moving to Harrison's Landing soon after the end of the Battle of Malvern Hill.
Starting at about 11 p.m. unit after unit began to follow.
Within hours, nearly all of McClellan's Army of the Potomac was marching towards Harrison's Landing.
Once the last of these men had crossed the Turkey Island Bridge, they destroyed the bridge and felled trees over it to stymie any pursuit, leaving the James River between the Union and Confederate armies.

The areas around Malvern Hill hosted much of Lee's army the night after the battle.
Some of the Confederates were close enough to hear the sounds made by the Army of the Potomac retreating under cover of darkness, and see the lanterns of Northerners helping their wounded.
The day after the Battle of Malvern Hill, Lee and Stonewall Jackson met President Jefferson Davis at Poindexter farm.
They considered immediately pursuing McClellan; however, in view of the rain and confusion, Davis and Lee deemed large-scale pursuit of McClellan's army too risky.
Jackson disagreed, saying, "They have not all got away if we go immediately after them."
Jackson even had the bodies of the dead moved so his soldiers had a clear line of attack when pursuing McClellan.
However, Davis and Lee thought it necessary to rest the army.
They did not completely rule out a pursuit though; Lee even ordered J. E. B. Stuart to reconnoiter McClellan's position for future attacks.
Lee ordered Theophilus Holmes to move to Drewry's Bluff, and decided to keep the men on Malvern Hill through July 3 to forestall any potential Union attack against that location.

On July 4, 1862, Lee's men began marching towards Harrison's Landing.
He made his headquarters a few miles north of Evelington Heights, a sixty-foot (18 m) elevation approximately thirteen miles (21 km) from Harrison's Landing, and stayed nearby with his army for several days, searching for weaknesses in the Union line at the heights that might allow for an attack.
No weakness presented itself though, and by the end of July 8, the entire Army of Northern Virginia, save for cavalry stations and picket forces, was back near Richmond.
The Peninsula Campaign was over.
Despite the strength of Malvern Hill, as demonstrated in the battle, McClellan felt he needed to continue with his planned withdrawal to Harrison's Landing, to Fitz John Porter's chagrin. Porter felt the Army of the Potomac should remain atop the hill or perhaps even continue their advance to Richmond. McClellan however insisted that Confederate troops greatly outnumbered his own, felt he could not protect Harrison's Landing from his current position at Malvern Hill, and feared being cut off from his supply depot. McClellan's mentality prevailed. The Union batteries and McClellan's engineers began moving to Harrison's Landing soon after the end of the Battle of Malvern Hill. Starting at about 11 p.m. unit after unit began to follow. Within hours, nearly all of McClellan's Army of the Potomac was marching towards Harrison's Landing. Once the last of these men had crossed the Turkey Island Bridge, they destroyed the bridge and felled trees over it to stymie any pursuit, leaving the James River between the Union and Confederate armies.
The areas around Malvern Hill hosted much of Lee's army the night after the battle. Some of the Confederates were close enough to hear the sounds made by the Army of the Potomac retreating under cover of darkness, and see the lanterns of Northerners helping their wounded. The day after the Battle of Malvern Hill, Lee and Stonewall Jackson met President Jefferson Davis at Poindexter farm. They considered immediately pursuing McClellan; however, in view of the rain and confusion, Davis and Lee deemed large-scale pursuit of McClellan's army too risky. Jackson disagreed, saying, "They have not all got away if we go immediately after them." Jackson even had the bodies of the dead moved so his soldiers had a clear line of attack when pursuing McClellan. However, Davis and Lee thought it necessary to rest the army. They did not completely rule out a pursuit though; Lee even ordered J. E. B. Stuart to reconnoiter McClellan's position for future attacks. Lee ordered Theophilus Holmes to move to Drewry's Bluff, and decided to keep the men on Malvern Hill through July 3 to forestall any potential Union attack against that location.
On July 4, 1862, Lee's men began marching towards Harrison's Landing. He made his headquarters a few miles north of Evelington Heights, a sixty-foot (18 m) elevation approximately thirteen miles (21 km) from Harrison's Landing, and stayed nearby with his army for several days, searching for weaknesses in the Union line at the heights that might allow for an attack. No weakness presented itself though, and by the end of July 8, the entire Army of Northern Virginia, save for cavalry stations and picket forces, was back near Richmond. The Peninsula Campaign was over.
Battle of Malvern Hill