When McClellan set off on his grand campaign to end the war, the Pennsylvania Reserves were not among them. They remained with McDowell's corps in the Fredericksburg vicinity. In June, the Reserves received orders to join McClellan in front of Richmond. Assigned to Fitz John Porter’s 5th Corps, the Pennsylvania Reserves assumed a position north of the Chickahominy River near Mechanicsville, on the right flank of McClellan's army.
Lee’s army attacked on June 26 in the opening battle of what would be called the Seven Days. Although the 5th Corps had successfully defended their position at Mechanicsville, Porter's men withdrew the next morning to a position behind Boatswain’s Swamp. The Pennsylvania Reserves took a reserve position behind this new line. The Battle of Gaines’s Mill was fought on June 27. The Confederate assaults began at about 2:30 that afternoon and continued all day. As the reserve, McCall’s regiments were fed into the fighting in a piecemeal fashion. By evening, Stonewall Jackson’s men were finally in a position to outflank Porter, and John Bell Hood’s furious frontal assault had finally pierced the Union center. The bluecoats were in full retreat toward the Chickahominy bridges. In the confusion, one of Meade's regiments, the 11th Pennsylvania Reserves, was surrounded and captured. Reynolds was also separated from his command and taken prisoner.
During the next week the Army of the Potomac continued its retreat toward the James River, fighting a significant engagement nearly every day. The Pennsylvania Reserves were assigned to escort the Artillery Reserve through White Oak Swamp to the Quaker Road on June 29.
The Reserves were ordered to take a position on June 30 to allow the army’s trains to pass to the rear. The Confederates launched an attack. If properly coordinated and executed, the resulting Battle of Glendale offered Robert E. Lee perhaps the finest opportunity he would ever have to destroy a large portion of the Army of the Potomac and perhaps end the war. Edward Porter Alexander, who would rise to prominence in the Confederate army, would later wrote of the fighting at Glendale: “No more desperate encounter took place in the war; and nowhere else, to my knowledge, so much actual fighting with bayonet and butt of gun.” Meade later asserted that “It was only the stubborn resistance offered by our division, prolonging the contest till after dark, and checking till that time the advance of the enemy, that enabled the concentration during the night of the whole army on the James River, that saved it.” one of Meade's aides, Lieutenant Hamilton Kuhn, was killed during the fighting, and another (Lieutenant Watmough) wounded.
During the fighting, Meade was severely wounded when a bullet struck him in the upper right side, traveling down and exiting above his hip. He was also hit in the right arm. He began to ride to the rear before growing faint from the loss of blood. He was placed in a small wagon and continued to the rear. After midnight, Meade arrived at Haxall’s Landing where Brigadier General Seth Williams, the Army of the Potomac’s adjutant general, gave Meade his tent. Later that day, Meade wrote a short note to his wife: "After four days' fighting, last evening, about 7 P. M., I received a wound in the arm and back. Fortunately I met Dr. Stocker, and got hold of a little cart I had, in which I was brought here. Dr. Stocker says my wounds are not dangerous, though they require immediate and constant medical attendance. I am to leave in the first boat for Old Point, and from thence home. Kuhn, I fear, is killed. Willie Watmough was not hurt, the last I saw of him. Good-by!" Someone addes a postscript: "The ball entered the side and came out at the back. In the hurried examination he probably heard, or was told, that he had been struck in the back. This seemed to worry him more than the fact of being wounded, for all through the watches of the long night he would revert to the thought, saying to Dr. Stocker, “Just think, doctor, of my being shot in the back!”
Meade was evacuated from the Peninsula, arriving at his home in Philadelphia on July 4. After a few weeks of rest and recovery, Meade returned to the Reserves on August 17, now at Aquia Creek and assigned to McDowell’s Corps in John Pope's Army of Virginia. The division command went to Reynolds, and Meade was assigned to command the First Brigade (3rd, 4th, 7th, 8th, and 13th Pennsylvania Reserves).
Meade's brigade played a prominent part in the disastrous Second Battle of Bull Run. The Reserves occupied a position on Henry House Hill, blunting the momentum of Longstreet's assault on August 30 and allowing Pope’s defeated army to retreat safely toward Washington. “In a few words we have been, as usual
out-manoeuvred and
out-numbered,” Meade reported to his wife, “and though not actually defeated, yet compelled to fall on Washington for its defense and our own safety.” Meade believed his performance at Second Bull Run warranted a promotion to command of a division.
With Union forces around in Washington in disarray, Lee took the opportunity to cross the Potomac and invade the North for the first time. As the Army of the Potomac marched north and west from Washington with McClellan back in command, Joseph Hooker assumed command of the redesignated First Corps and Meade found himself in command of the Pennsylvania Reserves when Reynolds was sent to Pennsylvania to assume command of the state militia.