Prelude to the Battle
On March 17, 1862, Union General George B. McClellan launched his Peninsula Campaign. After transporting the Army of the Potomac by ships to the Virginia peninsula between the York and James Rivers, McClellan planned to advance on Richmond and bring the American Civil War to a quick conclusion. By late May, the Federals had fought their way to the outskirts of the Confederate capital.
Battle of Seven Pines
On May 31, Confederate General Joseph E. Johnston struck back at the Battle of Seven Pines. Two days of hard fighting rendered a tactical draw and high casualties on both sides. The aftermath of the engagement, however, produced two important strategic developments. First, Robert E. Lee assumed command of the Army of Northern Virginia after Johnston suffered a severe wound during the fighting. Second, the high casualty rate convinced McClellan to invest Richmond rather than to risk costly assaults against the Rebel defenses around the capital.
Reprieve for Lee
For nearly a month, McClellan sat idly, developing plans for a siege. The unexpected reprieve presented Lee with an opportunity to organize his command and to plan an offensive designed to drive the Union army away from Richmond. Toward the end of June, McClellan developed a renewed sense of urgency when he learned that Major General Stonewall Jackson was moving to reinforce Lee after concluding his highly successful Shenandoah Valley Campaign.
Battle of Oak Grove
On June 25, at the Battle of Oak Grove, Rebel forces repulsed McClellan’s attempt to advance his siege artillery approximately one and one-half miles closer to the capital so he could “shell the city and take it by assault.”
Lee Seizes the Initiative at Beaver Dam Creek
Focus on Porter’s 5th Corps
On the next day, Lee seized the initiative. Leaving only two divisions to protect Richmond from the bulk of McClellan’s army (four corps positioned south of the Chickahominy River), Lee focused on defeating Brigadier General Fitz John Porter’s 5th Corps, isolated north of the river. Lee’s plan was to defeat Porter’s corps, which formed the right (northern) wing of the Federal army, and then to sever McClellan’s supply line, the York and Richmond Railroad.
Lee’s plan depended upon coordinated assaults by Major General Stonewall Jackson and Major General A. P. Hill. Jackson’s men were to attack and turn Porter’s right flank, forcing the Union general to reinforce his lines with troops stationed at the village of Mechanicsville just north of the Chickahominy River. Meanwhile, Hill’s men would cross the river, take Mechanicsville, and then assault Union defensive works behind Beaver Dam Creek, a short tributary of the Chickahominy.
Federals Repulse Rebels
Events did not unfold as Lee had planned. Jackson’s men, weary from their trip from the Shenandoah Valley, did not arrive on time. By 3 p.m., an impatient Hill crossed the Chickahominy and started the battle without Jackson’s support. The Yankees stationed at Mechanicsville gave way to Hill’s frontal assault and withdrew to the Federal defensive works along Beaver Dam Creek near Ellerson’s Mill. There, Porter’s 14,000 Bluecoats, supported by heavy artillery, repulsed Hill’s repeated charges, inflicting heavy casualties on the Rebels.
Meanwhile, Jackson finally arrived near the site of the fighting around 5 p.m. Despite hearing the sounds of the battle three or four miles ahead, Jackson inexplicably ordered his men to make camp for the night. Left to his own resources, Hill attempted one more frontal assault at dusk, which the Northerners also repulsed. The fighting subsided at nightfall.
Aftermath of the Battle
Lee’s first battle as commander of the Army of Northern Virginia was a total tactical failure. Of the 60,000 soldiers he amassed to overpower Porter’s isolated corps, only 16,000 were engaged at the Battle of Beaver Dam Creek. The uncoordinated assault failed to threaten McClellan’s supply lines, and Hill’s repeated attacks lost over 1,300 soldiers, compared with fewer than four hundred casualties for the Federals.
McClellan turned the Confederate defeat into a strategic victory for Lee. Characteristically overestimating the strength of his enemy, McClellan ordered Porter to abandon his entrenchments at Beaver Dam Creek during the night and to fall back to higher ground near Gaines’ Mill. In addition, McClellan shifted his supply line to the James River, abandoning the railroad and giving Lee what he did not achieve on the battlefield. McClellan’s decisions after the Battle of Beaver Dam Creek started a pattern of retreat that did not end until Lee drove the Army of the Potomac back to the banks of the James River in less than one week.