A few days prior to the action on Malvern Hill, McClellan incorrectly believed the Army of the Potomac was vastly outnumbered by its Confederate foe, and his fear of being cut off from his supply depot left him cautious and wary.
On the night of June 28, McClellan told his generals he intended to move his army to a position on the north bank of the James River called Harrison's Landing, where they would be protected by Union gunboats.
The Army of the Potomac came to Malvern Hill, the army's final stop before reaching the Landing, with approximately 54,000 men.

On the morning of June 30, 1862, the Union V Corps under Fitz John Porter, a part of McClellan's Army of the Potomac, amassed atop Malvern Hill.
Col.
Henry Hunt, McClellan's skilled chief of artillery, posted 171 guns on the hill and 91 more in reserve in the south.
The artillery line on the hill's slope consisted of eight batteries of field artillery with 37 guns.
Brig.
Gen. George Sykes's division would guard the line.
In reserve were additional field artillery and three batteries of heavy artillery, which included five 4.5-inch (11 cm) Rodman guns, five 20-pounder (9.1 kg) Parrott rifles and six 32-pounder (15 kg) howitzers.
As more of McClellan's forces arrived at the hill, Porter continued to reinforce the Union line.
Brig.
Gen. George Morell's units, stationed between the Crew and West farms, extended the line to the northeastern section.
Brig.
Gen. Darius Couch's division of the IV Corps, as yet unbloodied by the skirmishes of the Seven Days, further extended the northeastern line.
This left 17,800 soldiers from Couch's and Morell's divisions at the northern face of the hill, overlooking the Quaker Road, from which the Federals expected Lee's forces to attack.

Early the next day, Tuesday, July 1, McClellan, having come from nearby Haxall's Landing the night before, examined his army's battle line on Malvern Hill.
His inspection left him worried most about the Union Army's right (eastern) flank, which lay behind Western Run.
Western Run was an area necessary for McClellan's plans to relocate to Harrison's Landing, and he feared an attack might come from there.
As a result, he posted the largest portion of his army there: two divisions from Edwin Sumner's II Corps, two divisions from Brig.
Gen. Samuel P. Heintzelman's III Corps, two divisions from Brig.
Gen. William Franklin's VI Corps and one division from Maj.
Gen. Erasmus Keyes's IV Corps, who were stationed across the James.
The division under Brig.
Gen. George McCall, badly mangled in the fighting at Glendale and having lost McCall and two of its three brigadiers, was held in general reserve.

McClellan did not believe his army was ready for a battle, and hoped Lee would not give them one.
Nonetheless, he left his troops at Malvern Hill and traveled downstream aboard the ironclad USS Galena to inspect his army's future resting place at Harrison's Landing.
McClellan did not delegate an interim commander; Porter, who was in command during the initial attack, became the de facto leader on the Union side of the battle.
A few days prior to the action on Malvern Hill, McClellan incorrectly believed the Army of the Potomac was vastly outnumbered by its Confederate foe, and his fear of being cut off from his supply depot left him cautious and wary. On the night of June 28, McClellan told his generals he intended to move his army to a position on the north bank of the James River called Harrison's Landing, where they would be protected by Union gunboats. The Army of the Potomac came to Malvern Hill, the army's final stop before reaching the Landing, with approximately 54,000 men.
On the morning of June 30, 1862, the Union V Corps under Fitz John Porter, a part of McClellan's Army of the Potomac, amassed atop Malvern Hill. Col. Henry Hunt, McClellan's skilled chief of artillery, posted 171 guns on the hill and 91 more in reserve in the south. The artillery line on the hill's slope consisted of eight batteries of field artillery with 37 guns. Brig. Gen. George Sykes's division would guard the line. In reserve were additional field artillery and three batteries of heavy artillery, which included five 4.5-inch (11 cm) Rodman guns, five 20-pounder (9.1 kg) Parrott rifles and six 32-pounder (15 kg) howitzers. As more of McClellan's forces arrived at the hill, Porter continued to reinforce the Union line. Brig. Gen. George Morell's units, stationed between the Crew and West farms, extended the line to the northeastern section. Brig. Gen. Darius Couch's division of the IV Corps, as yet unbloodied by the skirmishes of the Seven Days, further extended the northeastern line. This left 17,800 soldiers from Couch's and Morell's divisions at the northern face of the hill, overlooking the Quaker Road, from which the Federals expected Lee's forces to attack.
Early the next day, Tuesday, July 1, McClellan, having come from nearby Haxall's Landing the night before, examined his army's battle line on Malvern Hill. His inspection left him worried most about the Union Army's right (eastern) flank, which lay behind Western Run. Western Run was an area necessary for McClellan's plans to relocate to Harrison's Landing, and he feared an attack might come from there. As a result, he posted the largest portion of his army there: two divisions from Edwin Sumner's II Corps, two divisions from Brig. Gen. Samuel P. Heintzelman's III Corps, two divisions from Brig. Gen. William Franklin's VI Corps and one division from Maj. Gen. Erasmus Keyes's IV Corps, who were stationed across the James. The division under Brig. Gen. George McCall, badly mangled in the fighting at Glendale and having lost McCall and two of its three brigadiers, was held in general reserve.
McClellan did not believe his army was ready for a battle, and hoped Lee would not give them one. Nonetheless, he left his troops at Malvern Hill and traveled downstream aboard the ironclad USS Galena to inspect his army's future resting place at Harrison's Landing. McClellan did not delegate an interim commander; Porter, who was in command during the initial attack, became the de facto leader on the Union side of the battle.
Battle of Malvern Hill