The Seven Days Battles were a series of seven battles over seven days from June 25 to July 1, 1862, near Richmond, Virginia, during the American Civil War. Confederate General Robert E. Lee drove the invading Union Army of the Potomac, commanded by Maj. Gen. George B. McClellan, away from Richmond and into a retreat down the Virginia Peninsula. The series of battles is sometimes known erroneously as the Seven Days Campaign, but it was actually the culmination of the Peninsula Campaign, not a separate campaign in its own right.

The Seven Days began on Wednesday, June 25, 1862, with a Union attack in the minor Battle of Oak Grove, but McClellan quickly lost the initiative as Lee began a series of attacks at Beaver Dam Creek (Mechanicsville) on June 26, Gaines's Mill on June 27, the minor actions at Garnett's and Golding's Farm on June 27 and 28, and the attack on the Union rear guard at Savage's Station on June 29. McClellan's Army of the Potomac continued its retreat toward the safety of Harrison's Landing on the James River. Lee's final opportunity to intercept the Union Army was at the Battle of Glendale on June 30, but poorly executed orders and the delay of Stonewall Jackson's troops allowed his enemy to escape to a strong defensive position on Malvern Hill. At the Battle of Malvern Hill on July 1, Lee launched futile frontal assaults and suffered heavy casualties in the face of strong infantry and artillery defenses.

The Seven Days ended with McClellan's army in relative safety next to the James River, having suffered almost 16,000 casualties during the retreat. Lee's army, which had been on the offensive during the Seven Days, lost over 20,000. As Lee became convinced that McClellan would not resume his threat against Richmond, he moved north for the northern Virginia campaign and the Maryland campaign.

The Peninsula campaign was the unsuccessful attempt by McClellan to capture the Confederate capital of Richmond and end the war. It started in March 1862, when McClellan landed his army at Fort Monroe and moved northwest, up the Virginia Peninsula beginning in early April. Confederate Brig. Gen. John B. Magruder's defensive position on the Warwick Line caught McClellan by surprise. His hopes for a quick advance foiled, McClellan ordered his army to prepare for a siege of Yorktown. Just before the siege preparations were completed, the Confederates, then under the direct command of Johnston, began a withdrawal toward Richmond.

The first heavy fighting of the campaign occurred in the Battle of Williamsburg (May 5), in which the Union troops managed some tactical victories, but the Confederates continued their withdrawal. An amphibious flanking movement to Eltham's Landing (May 7) was ineffective in cutting off the Confederate retreat. In the Battle of Drewry's Bluff (May 15), an attempt by the United States Navy to reach Richmond by way of the James River was repulsed.

As McClellan's army reached the outskirts of Richmond, a minor battle occurred at Hanover Court House (May 27), but it was followed by a surprise attack by Johnston at the Battle of Seven Pines or Fair Oaks on May 31 and June 1. The battle was inconclusive, with heavy casualties, but it had lasting effects on the campaign. Johnston was wounded and replaced on June 1 by the more aggressive Robert E. Lee. Lee spent almost a month extending his defensive lines and organizing his Army of Northern Virginia; McClellan accommodated this by sitting passively to his front, waiting for dry weather and roads, until the start of the Seven Days. Lee, who had developed a reputation for caution early in the war, knew he had no numerical superiority over McClellan, but he planned an offensive campaign that was the first indication of the aggressive nature he would display for the remainder of the war.

Lee's initial attack plan, similar to Johnston's plan at Seven Pines, was complex and required expert coordination and execution by all of his subordinates, but Lee knew that he could not win in a battle of attrition or siege against the Union Army. It was developed at a meeting on June 23. The Union Army straddled the rain-swollen Chickahominy River, with the bulk of the army, four corps, arrayed in a semicircular line south of the river. The remainder, the V Corps under Brig. Gen. Fitz John Porter, was north of the river near Mechanicsville in an L-shaped line facing north–south behind Beaver Dam Creek and southeast along the Chickahominy. Lee's plan was to cross the Chickahominy with the bulk of his army to attack the Union north flank, leaving only two divisions (under Maj. Gens. Benjamin Huger and John B. Magruder) to hold a line of entrenchments against McClellan's superior strength. This would concentrate about 65,500 troops to oppose 30,000, leaving only 25,000 to protect Richmond and to contain the other 60,000 men of the Union Army. The Confederate cavalry under Brig. Gen. J.E.B. Stuart had reconnoitered Porter's right flank—as part of a daring but militarily dubious circumnavigation of the entire Union Army from June 12 to 15—and found it vulnerable.

Lee intended for Jackson to attack Porter's right flank early on the morning of June 26, and A.P. Hill would move from Meadow Bridge to Beaver Dam Creek, which flows into the Chickahominy, advancing on the Federal trenches. (Lee hoped that Porter would evacuate his trenches under pressure, obviating the need for a direct frontal assault.) Following this, Longstreet and D.H. Hill would pass through Mechanicsville and join the battle. Huger and Magruder would provide diversions on their fronts to distract McClellan as to Lee's real intentions. Lee hoped that Porter would be overwhelmed from two sides by the mass of 65,000 men, and the two leading Confederate divisions would move on Cold Harbor and cut McClellan's communications with White House Landing.