American Civil War: Battle of Gaines' Mill

Robert E. Lee
General Robert E. Lee, CSA. Photograph Courtesy of the National Archives & Records Administration

Battle of Gaines' Mill - Conflict & Dates:

The Battle of Gaines' Mill was fought June 27, 1862, during the American Civil War and was the second of the Seven Days Battles.

Armies & Commanders



Battle of Gaines' Mill - Background:

Having shifted the Army of the Potomac south to the Peninsula in the spring of 1862, Union Major General George B.

McClellan began a slow advance on the Confederate capital of Richmond. Pushing inland, he was tricked by Major General John Magruder into spending much of April laying siege to Yorktown. Overcoming this obstacle, McClellan engaged the enemy at Williamsburg in early May before fighting the Battle of Seven Pines outside Richmond at the end of the month. In the course of the fighting, Confederate commander General Joseph E. Johnston was badly wounded and leadership of the army ultimately passed to General Robert E. Lee.

While McClellan, who incorrectly believed his army to be outnumbered, remained idle for much of June, Lee worked tirelessly to improve Richmond's defenses and plan a counterattack. Though outnumbered himself, Lee understood his army could not hope to win a protracted siege at Richmond. On June 25, McClellan finally stirred and he directed the divisions of Brigadier Generals Joseph Hooker and Philip Kearny to attack up the Williamsburg Road.

The resulting Battle of Oak Grove saw the Union thrust blocked by Major General Benjamin Huger's division. This proved fortuitous for Lee as he had transferred the bulk of his army north of the Chickahominy River with the goal of destroying Brigadier General Fitz John Porter's isolated V Corps.

Battle of Gaines' Mill - Lee Attacks:

On June 26, Lee intended to assault Porter from the north with Major General Thomas "Stonewall" Jackson's command while the divisions of Major Generals A.P. Hill, James Longstreet, and D.H. Hill attacked in support.

The plan quickly collapsed as Jackson ran late and never engaged. Despite this, A.P. Hill moved forward and opened the Battle of Beaver Dam Creek (Mechanicsville). Later supported by additional Confederate forces, Hill was repeatedly repulsed by Porter's men and took heavy losses. Though a tactical victory, McClellan became concerned about Jackson's presence to the north which threatened his main supply line, the Richmond and York River Railroad, which ran back to White House Landing on the Pamunkey River.

Battle of Gaines' Mill - McClellan Responds:

As a result, early on June 27 McClellan ordered Porter to fall back to a new position behind Boatswain's Swamp and near Gaines' Mill. More importantly, he directed that the Army of the Potomac's supply line be transferred south to the James River. In making this switch, McClellan effectively defeated his own campaign as the abandonment of the railroad meant that heavy artillery could not be brought to Richmond for the anticipated siege. As events progressed, he also failed to realize that he possessed a massive numerical advantage south of the Chickahominy. This was partially due to the efforts of Huger's and Magruder's divisions which conducted ruses to make their numbers appear inflated.

Battle of Gaines' Mill - Lee's Plan:

Falling back, Porter established a strong line behind Boatswain's Swamp with Brigadier General George Morell's division on the left and Brigadier General George Sykes' division on the right. The division of Brigadier General George McCall was held in reserve. Thwarted on June 26, Lee wished to retain the initiative and began planning a new series of attacks for the next day. His plan of attack was similar to the previous day and called for Jackson and D.H. Hill to strike Porter's right and rear while Longstreet and A.P. Hill applied pressure from the west. Traveling to Walnut Grove Church, Lee briefed Jackson on the plan but provided incorrect information as he believed Porter's line to be further west along Powhite Creek.

Battle of Gaines' Mill - First Shots:

Though lacking time to entrench, Porter's deployment made superb use of the terrain and provided his infantry and artillery with open fields of fire.

Around 1:00 PM, D.H. Hill reached Old Cold Harbor where his division was supposed to meet Jackson. As on the previous day, Jackson was running behind and Hill elected to push south on his own. His men soon came under heavy fire from the US Regulars of Sykes' division. Believing that he should past the Union flank, the level of resistance surprised him and halted his advance to wait for Jackson. Around this time, A.P. Hill pushed across Beaver Dam Creek and neared Gaines' Mill. Sensing the enemy pressure increasing, Porter requested reinforcements and received Brigadier General Henry Slocum's division from Brigadier General William Franklin's VI Corps.

Battle of Gaines' Mill - Porter Assaulted:

Pushing through Union skirmishers, A.P. Hill's division reached Boatswain's Swamp and moved to assault the Union line. Slowed by the marshy terrain, its first efforts against Porter's line were repulsed with heavy losses (Map). Though initially buoyed by Porter's reports from above the Chickahominy, McClellan began preparing for a further retreat when Brigadier General Edwin Sumner, commander of II Corps, informed him of increased enemy activity south of the river. Arriving to the southwest of A.P. Hill, Longstreet saw the difficulty his comrade's men were having and elected to remain stationary until Jackson was in place to offer support.

Overcoming several delays, Jackson's lead division, led by Major General Richard Ewell finally reached the field and went into action. Struggling through the swampy landscape, his men were turned back by the Union troops.

Concerned that Porter might counterattack A.P. Hill's battered command, Lee also directed Longstreet to attack on the right to stabilize the Confederate line. These efforts, particularly an assault by Brigadier General George Pickett's brigade were bloodily repulsed (Map). Increasingly outnumbered, Porter continued to request assistance from McClellan. Concerned about Confederate forces below the Chickahominy, the Union commander delayed before finally releasing two brigades north.

Battle of Gaines' Mill - Porter Overwhelmed:

Finally arriving on the scene, Jackson began arraying his forces for a coordinated assault the other Confederate units. Meeting with Lee on the Telegraph Road, the two generals discussed the operation in detail. Moving forward at 7:00 PM, Lee attacked Porter with over 30,000 men in the largest single assault he mounted during the war. Striking with a force nearly equal in size to the tire V Corps, the Confederates continued to take substantial losses from the staunch Union defense. With the sun beginning to set, Brigadier General William Whiting's division achieved the first breakthrough on Longstreet's front. Led by Brigadier General John B. Hood's Texas Brigade, the Confederates opened a gap in the Union line (Map).

This was followed by other breakthroughs as V Corps was overwhelmed. With his position crumbling, Porter began retreating from Boatswain's Swamp. With Sykes and the newly arrived brigades of Brigadier Generals Thomas F. Meagher and William H.

French serving as a rearguard, Porter began moving his men south and across the Chickahominy. By 4:00 AM on July 28, his men were over the river and Porter directed the bridges to be burned.

Battle of Gaines' Mill - Aftermath:

In the fighting at Gaines' Mill, Porter's V Corps inflicted 1,483 killed, 6,402 wounded, and 108 missing/captured on Lee's army while sustaining 894 killed, 3,107 wounded, and 2,836 captured/ missing. Lee's first major triumph of the war, the Battle of Gaines' Mill was the Confederacy's only clear tactical victory of the campaign. The defeat at Gaines' Mill badly unnerved the already cautious McClellan and caused the Union general to abandon his campaign on Richmond and seek the safety of the James River. With the threat to Richmond removed, Lee focused on inflicting a damaging defeat on the Army of the Potomac. On June 29, he renewed the fighting when he attacked McClellan at Savage's Station.

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