The delay was due mainly to the deep mud caused by a heavy rain the night before. Later in the day, General Winfield S. Hancock's brigade made a wide circuit on the right, discovered some unoccupied redoubts, and took possession of them. When the Confederates advanced their left to the attack, they ran upon these redoubts, which their commanding officers knew nothing about, and were repelled with heavy loss. Hancock's one thousand six hundred men suddenly burst over the crest of the works, and bore down upon the enemy with fixed bayonets, routing and scattering them. McClellan brought up reinforcements, and in the night the Confederates in front of him moved off to join their main army, leaving in Williamsburg four hundred of their wounded, because they had no means of carrying them away, but taking with them about that number of prisoners. The National loss had been about two thousand two hundred, the Confederate about one thousand eight hundred.
General Franklin's division of McDowell's corps had now been sent to McClellan, and immediately after the Battle of Williamsburg he moved it on transports to White House, at the head of York River, where it established a base of supplies. As soon as possible, also, the main body of the army was marched from Williamsburg to White House, reaching that place on May 16th. From this point he moved westward toward Richmond, expecting to be joined by a column of forty thousand men under McDowell, which was to move from Fredericksburg. On reaching the Chickahominy, McClellan threw his left wing across that stream, and sweeping around with his right fought small battles at Mechanicsville and Hanover junction, by which he cleared the way for McDowell to join him. But at this critical point of time Stonewall Jackson suddenly made another raid down the Shenandoah Valley, and McDowell was called back to pursue him.
Johnston resolved to strike the detached left wing of the National army, which had crossed the Chickahominy and advanced within half a dozen miles of Richmond, and his purpose was seconded by a heavy rain on the night of May 30th, which swelled the stream and swept away some of the bridges, thus hindering reinforcement from the other wing. The attack, May 31st, fell first upon General Silas Casey's division of Keyes's corps, which occupied some half-finished works. It was bravely made and bravely resisted, and the Confederates suffered heavy losses before these works, where they had almost surprised the men with the shovels in their hands. But after a time a Confederate force made a detour and gained a position in the rear of the redoubts, when of course they could be held no longer. Reinforcements were very slow in coming up, and Keyes's men had a long, hard struggle to hold their line at all. They could not have done so if a part of Johnston's plan had not miscarried. He intended to bring in a heavy flanking force between them and the river, but was delayed several hours in getting it in motion.
Meanwhile McClellan ordered Sumner to cross the river and join in the battle. Sumner had anticipated such in order as soon as he heard the firing, and when the order came it found him with his corps in line, drawn out from camp, and ready to cross instantly. He was the oldest officer there (sixty-six), and the most energetic. There was but one bridge that could be used: many of the supports of this were gone, the approaches were under water, and it was almost a wreck. But he unhesitatingly pushed on his column. The frail structure was steadied by the weight of the men; and though it swayed and undulated with their movement and the rush of the water, they all crossed in safety.
Sumner was just in time to meet the flank attack, which was commanded by Johnston in person. The successive charges of the Confederates were all repelled, and at dusk a counter charge cleared the ground in front and drove off the last of them in confusion. In this fight General Johnston received wounds that compelled him to retire from the field and laid him up for a long time. The battle - which is called both Fair Oaks and Seven Pines - cost the National army more than five thousand men, and the Confederate nearly seven thousand.
For some time after the Battle of Fair Oaks heavy rains made any movement almost impossible for either off the armies that confronted each other near Richmond. General Alexander S. Webb says: "The ground, which consisted of alternate layers of reddish clay and quicksand, had turned into a vast swamp and the guns in battery sank into the earth by their own weight."
“Therefore encourage one another and build each other up, just as in fact you are doing.”
– 1 Thessalonians 5:11