In late June 1862 the Union Army of the Potomac was close enough to Richmond to hear its church bells, yet within a week it was retreating to the James River. George B. McClellan had more than 100,000 men but believed Pinkerton reports that he faced 200,000. Robert E. Lee, in command only since June 1 after Joseph E. Johnston’s wounding at Seven Pines and mocked as the King of Spades, had about 90,000 men and chose to attack rather than endure a siege.

After Oak Grove on June 25, A.P. Hill’s unsupported assault at Beaver Dam Creek was repulsed, yet McClellan decided that night to abandon his railroad supply line. Gaines’ Mill, the largest Confederate attack of the war, broke the Union line, and McClellan boarded a Navy gunboat on June 29 without naming a second in command. Lee’s trap at Glendale failed, and on July 1 Henry Hunt’s massed artillery on Malvern Hill shattered the Confederate assaults. The week cost nearly 16,000 Union and more than 20,000 Confederate casualties.

• Pinkerton’s agents estimated enemy strength partly by counting Confederate campfires.
• Stonewall Jackson arrived hours late at Mechanicsville and spent a day at White Oak Swamp trying to rebuild a bridge.
• Benjamin Huger had his men cut a new road through the woods around felled trees and missed Glendale.
• Henry Hunt massed 250 cannons on Malvern Hill, and Confederate infantry never got within 200 yards of the Union center.
• Lee reorganized his army into two corps under James Longstreet and Stonewall Jackson after the campaign.