The delay saved Richmond. Every day reinforcements arrived, and by the time that McClellan's army, over 100,000 strong, had erected their batteries and got their heavy guns into position, Magruder had been reinforced by some 10,000 men under General Johnston, who now assumed the command, while other divisions were hurrying up from Northern and Western Virginia. Upon the very night before the batteries were ready to open, the Confederates evacuated their positions and fell back, carrying with them all their guns and stores to the Chickahominy River, which ran almost across the peninsula at a distance of six miles only from Richmond.

The Confederates crossed and broke down the bridges, and prepared to make another stand. The disappointment of the Federals was great. After ten days of incessant labor and hardship they had only gained possession of the village of Yorktown and a tract of low swampy country. The divisions in front pressed forward rapidly after the Confederates; but these had managed their plan so well that all were safely across the stream before they were overtaken.