Continuing on with our look at the Confederate offensive of the Seven Days, we come to the battle of Gaines Mill. After the battle of Mechanicsville, Lee assembled a Confederate attack force of six divisions, 57,000 men, for the largest Confederate attack of the War, aimed at Porter’s V Corps, McClellan neither sending sufficient units from south of the Chickahominy to reinforce Porter, nor attacking against the weak Confederate forces holding Richmond, McClellan paralyzed by his belief that he was massively outnumbered both north and south of the Chickahominy.
McClellan’s order for Porter to withdraw came just before dawn on the 27th. Numerous men in Brigadier General McCall’s division were captured by the Confederates due to the precipitate retreat necessary to comply with the order. Porter picked out a good defensive position on a plateau behind Boatswain’s Swamp to make his stand. He placed two divisions on the line and two divisions in reserve.
The battle began at 1:00 PM with a series of unsuccessful frontal assaults. Jackson on the Confederate left was late again and not in position to attack until the general assault of 7:00 PM. By this time the outnumbered Union troops were weary and the Union line crumpled up, Porter withdrawing in good order to the bridges over the Chickahominy, his corps crossing to the south side at 4:00 AM on June 28. The battle was a clear-cut Confederate victory, although their casualties of 7,933 were slightly greater than the Union casualties of 6, 833. The victory could have been greater if Jackson had been in position by 1:00 PM. A retreat by Porter with eight hours of daylight could easily have ended in the destruction of Porter’s Corps. As it was, McClellan was completely unnerved by the Confederate victory, and ordered a full retreat of his entire army from Richmond, which Lee and his army had saved.
Here is General Lee’s report on the Battle of Gaines Mill and its aftermath which was written on March 6, 1863:
BATTLE OF THE CHICKAHOMINY
After repairing the bridges over Beaver Dam the several columns resumed their march as nearly as possible as prescribed in the order; Jackson, with whom D. H. Hill had united, bore to the left, in order to cut off re-enforcements to the enemy or intercept his retreat in that direction. Longstreet and A. P. Hill moved nearer the Chickahominy. Many prisoners were taken in their progress, and the conflagration of wagons and stores marked the way of the retreating army. Longstreet and Hill reached the vicinity of New Bridge about noon. It was ascertained that the enemy had taken a position behind Powhite Creek, prepared to dispute our progress. He occupied a range of hills, with his right resting in the vicinity of McGehee’s house and his left near that of Dr. Gaines, on a wooded bluff, which rose abruptly from a deep ravine. The ravine was filled with sharpshooters, to whom its banks gave protection. A second line of infantry was stationed on the side of the hill behind a breastwork of trees above the first; a third occupied the crest, strengthened with rifle trenches and crowned with artillery. The approach to this position was over an open plain, about a quarter of a mile wide, commanded by this triple line of fire and swept by the heavy batteries south of the Chickahominy. In front of his center and right the ground was generally open, bounded on the side of our approach by a wood, with dense and tangled undergrowth, and traversed by a sluggish stream, which converted the soil into a deep morass. The woods on the farther side of the swamp were occupied by sharpshooters, and trees had been felled to increase the difficulty of its passage and detain our advancing columns under the fire of infantry massed on the slopes of the opposite hills and of the batteries on their crests. Pressing on toward the York River Railroad, A. P. Hill, who was in advance, reached the vicinity of New Cold Harbor about 2 p.m., where he encountered the enemy. He immediately formed his line nearly parallel to the road leading from that place toward McGehee’s house, and soon became hotly engaged. The arrival of Jackson on our left was momentarily expected, and it was supposed that his approach would cause the extension of the enemy’s line in that direction. Under this impression Longstreet was held back until this movement should commence. The principal part of the Federal Army was now on the north side of the Chickahominy. Hill’s single division met this large force with the impetuous courage for which that officer and his troops are distinguished. They drove the enemy back and assailed him in his strong position on the ridge. The battle raged fiercely and with varying fortune more than two hours. Three regiments pierced the enemy’s line and forced their way to the crest of the hill on his left, but were compelled to fall back before overwhelming numbers. The superior force of the enemy, assisted by the fire of his batteries south of the Chickahominy, which played incessantly on our columns as they pressed through the difficulties that obstructed their way, caused them to recoil. Though most of the men had never been under fire until the day before, they were rallied and in turn repelled the advance of the enemy. Some brigades were broken, others stubbornly maintained their positional but it became apparent that the enemy was gradually gaining ground.
The attack on our left being delayed by the length of Jackson’s march and the obstacles he encountered, Longstreet was ordered to make a diversion in Hill’s favor by a feint on the enemy’s left. In making this demonstration the great strength of the position already described was discovered, and General Longstreet perceived that to render the diversion effectual the feint must be converted into an attack. He resolved with characteristic promptness to carry the heights by assault. His column was quickly formed near the open ground, and as his preparations were completed Jackson arrived, and his right division, that of Whiting, took position on the left of Longstreet. At the same time D. H. Hill formed on our extreme left, and after a short but bloody conflict forced his way through the morass and obstructions and drove the enemy from the woods on the opposite side. Ewell advanced on Hill’s right and engaged the enemy furiously. The First and Fourth Brigades of Jackson’s own division filled the interval between Ewell and A. P. Hill. The Second and Third were sent to the right. The arrival of these fresh troops enabled A. P. Hill to withdraw some of his brigades, wearied and reduced by their long and arduous conflict. The line being now complete, a general advance from right to left was ordered. On the right the troops moved forward with steadiness, unchecked by the terrible fire from the triple lines of infantry on the hill, and the cannon on both sides of the river, which burst upon them as they emerged upon the plain. The dead and wounded marked the way of their intrepid advance, the brave Texans leading, closely followed by their no less daring comrades. The enemy were driven from the ravine to the first line of breastworks, over which our impetuous column dashed up to the intrenchments on the crest. These were quickly stormed, fourteen pieces of artillery captured, and the enemy driven into the field beyond. Fresh troops came to his support and he endeavored repeatedly to rally, but in vain. He was forced back with great slaughter until he reached the woods on the banks of the Chickahominy, and night put an end to the pursuit. Long lines of dead and wounded marked each stand made by the enemy in his stubborn resistance, and the field over which he retreated was strewn with the slain.
On the left the attack was no less vigorous and successful. D.H. Hill charged across the open ground in his front, one of his regiments having first bravely carried a battery whose fire enfiladed his advance. Gallantly supported by the troops on his right, who pressed forward with unfaltering resolution, he reached the crest of the ridge, and after a sanguinary struggle broke the enemy’s line, captured several of his batteries, and drove him in confusion toward the Chickahominy until darkness rendered farther pursuit impossible.
Our troops remained in undisturbed possession of the field, covered with the Federal dead and wounded, and their broken forces fled to the river or wandered through the woods.
Owing to the nature of the country the cavalry was unable to participate in the general engagement. It rendered valuable service in guarding Jackson’s flank and took a large number of prisoners.
On the morning of the 28th it was ascertained that none of the enemy remained in our front north of the Chickahominy. As he might yet intend to give battle to preserve his communications, the Ninth Cavalry, supported by Ewell’s division, was ordered to seize the York River Railroad, and General Stuart, with his main body, to co-operate. When the cavalry reached Dispatch Station the enemy retreated to the south bank of the river and burned the railroad bridge. Ewell, coming up shortly afterward, destroyed a portion of the track.
During the forenoon columns of dust south of the Chickahominy showed that the Federal Army was in motion. The abandonment of the railroad and destruction of the bridge proved that no further attempt would be made to hold that line; but’ from the position it occupied the roads which led toward James River would also enable it to reach the lower bridges over the Chickahominy and retreat down the peninsula. In the latter event it was necessary that our troops should continue on the north bank of the river, and until the intention of General McClellan was discovered it was deemed injudicious to change their disposition. Ewell was therefore ordered to proceed to Bottom’s Bridge to guard that point, and the cavalry to watch the bridges below. No certain indications of a retreat to James River were discovered by our forces on the south side of the Chickahominy, and late in the afternoon the enemy’s works were reported to be fully manned. The strength of these fortifications prevented Generals Huger and Magruder from discovering what was passing in their front. Below the enemy’s works the country was densely wooded and intersected by impassable swamps, at once concealing his movements and precluding reconnaiasances except by the regular roads, all of which were strongly guarded. The bridges over the Chickahominy in rear of the enemy were destroyed, and their reconstruction impracticable in the presence of his whole army and powerful batteries. We were therefore compelled to wait until his purpose should be developed.
Generals Huger and Magruder were again directed to use the utmost vigilance and pursue the enemy vigorously should they discover that be was retreating. During the afternoon and night of the 28th the signs of a general movement were apparent, and no indications of his approach to the lower bridges of the Chickahominy having been discovered by the pickets in observation at those points, it became manifest that General McClellan was retreating to the James River.