The experiences of a winter campaign in Virginia caused the Federals to await the spring to renew their efforts, and the two armies watched each other on the Rappahannock until towards the end of April 1863. Hooker, who had taken Burnside's place, then had 120,000 men opposed to Lee's 6o,000, and he planned, while leaving part of his army on the river, to occupy Lee's front, to march the remainder round the Confederate left and come down on their rear through the woods of Chancellorsville. Lee was once more well informed of his opponents' movements. Leav ing a detachment on the river he marched with the bulk of his troops, including Jackson's corps, towards Chancellorsville. On the outskirts of the wilderness of Chancellorsville Lee and Jack son made their plans on the night of May 1-2. Lee, with an under standing of the delaying power of entrenchments which no other soldier of his day possessed, proposed to repeat the manoeuvre which had opened the battles of the "Seven Days." Keeping only Io,000 men with himself entrenched opposite Hooker's front, he sent Jackson, under cover of the woods, round Hooker's right, which on the evening of May 2 was surprised and routed. Jackson fell mortally wounded, but Hooker was driven back over the Rappahannock.
Lee followed this victory by another invasion of Northern territory. He had been joined by Longstreet's corps, which brought his strength to 73,00o men, and early in June he began a brilliant series of manoeuvres across Hooker's front, which brought his army in the third week of that month into the northern end of the Shenandoah valley. There he detached Stuart with his cavalry to delay Hooker's crossing of the Potomac. It was Lee's intention that Stuart should return to cover his right flank, but by an unfortunate misunderstanding Stuart, who had made himself famous by a number of raids round the Federal army, crossed the Potomac to the east of the mountains and was separated from Lee for several days. Thus the Confederates entered Pennsylvania by way of the Cumberland valley deprived of their eyes, and in ignorance of the Federal movements. Hooker had crossed the Potomac to cover Washington, but Lincoln, realizing that he had been outmanoeuvred by Lee, replaced him by Meade.
It was not until June 29 that Lee learned that the Federal army was across the Potomac, and he at once began to concentrate his forces. The next day his flank guard came into collision with Federal cavalry near Gettysburg, and on July I both armies were converging on that place. That evening and on the morning of the 2nd the advantage was with the Confederates, for the Federal forces were arriving piecemeal, and there is little doubt but that if Longstreet had attacked on the morning of the 2nd, as Lee wished him to do, the Confederates would have been victorious.
But Longstreet, though a fine tactician, was an obstinate subordi nate, and found excuses for delay. By noon on July 2 the opportunity had passed, and Lee's attacks both on that day and on the 3rd were heavily repulsed. Lee thereupon skilfully retreated, and on July 14 was back in Virginia.
After Gettysburg both armies needed rest, and when Meade was once more ready to advance Lee had prepared strong defences along the Rapidan, which the Federals found too formidable for attack. So the winter passed with the two armies waiting for better weather to resume manoeuvre.
The result of Gettysburg was to change Lee's military policy.
Up to that battle he had hoped to force the North to make peace by winning a resounding victory in Northern territory. Af ter Gettysburg he understood that the South's resources would no longer justify that policy, and his plan became to exhaust by delay the patience of the North. In March 1864 Lincoln took the de cisive step of appointing Grant, the hero of Vicksburg, to the supreme command of the Federal armies. Grant, realizing that Lee and his army were the chief obstacle to the fulfilment of Federal aims and the superiority of the resources of the North, proposed to fasten on to Lee and compel him to fight on every possible occasion. By the beginning of May Grant had an army of 130,000 ready in northern Virginia, and on the night of May he began to cross the Rappahannock near Fredericksburg, hoping to force Lee to leave his lines on the Rapidan in order to cover Richmond. Lee waited until Grant was across the river, and then attacked, with 6o,000 men, Grant's flank as he was moving through the forest of the Wilderness. The forest country neutralized the effect of the superior Federal artillery, the South erners were better acquainted with the intricate country and the advantage was with the Confederates. But Grant would not acknowledge defeat, and knowing that his army was much stronger than that of Lee, he, instead of retreating as Hooker had done, broke off the battle and continued to advance towards Richmond.
Lee at once divined Grant's intention, and when the Federal ad vanced guard reached Spottsylvania court house on May 9 it found its way barred by entrenchments. There followed a nine days' battle of trench warfare, in which the Federal assaults were heavily repulsed. Grant then abandoned his efforts to force Lee's front, and once more marched past his flank, only to find, on May 23, Lee once more barring his way behind the North Anna. Again Grant marched past Lee's flank, and again on June I found Lee in position at Cold Harbor. Grant, apparently losing patience, on June 3 made a frontal attack on Lee's lines which failed with heavy loss.