The North had not yet found a general capable of commanding the superb army it had created, or of making effective use of those enormously superior resources which from the beginning had been at its disposal. Grant had splendidly demonstrated his capacity at Shiloh, but Halleck had immediately superseded him, and completely thrown away the opportunity there presented. Grant was still denied any but volunteer rank, and for many weeks after Shiloh he was left, as he has himself recorded, with none but nominal command, and was not even consulted by his immeasurably inferior superior.

McClellan at last reached the neighbourhood of Richmond, and placed his great army on the eastern and northern fronts of the Confederate capital. But still permitting his imagination to mislead him, he confidently believed the Confederate forces to be quite twice as numerous as they were in fact. So instead of pressing them vigorously, as a more enterprising and less excessively cautious commander would have done, he proceeded to fortify and for weeks kept his splendid army idle in a pestilential swamp, whose miasms were far deadlier than bullets and shells could have been.

At the end of May the Confederates assailed his left wing, believing that a flood in the river had isolated it from the rest of the army, and a bloody five days' battle ensued, with no decisive results, except to demonstrate the fighting quality of the troops under McClellan's command.

Still he hesitated and fortified, and urgently called for reinforcements. These to the number of forty thousand were on their way to join him, marching directly southward from Washington.

But the Confederates had been more fortunate than their foes. They had found their great commander, a piece of good fortune which did not happen to the Federal armies until nearly two years later. After the battle of Seven Pines at the end of May and the beginning of June, Robert E. Lee assumed personal command of the forces defending Richmond, and from that hour the great game of war was played by him with a sagacity and a boldness that had not been seen before.

Lee's problem was to drive McClellan's army away from Richmond, and transfer the scene of active hostilities to some more distant point. To that end he must prevent the coming of McDowell with his army to McClellan's assistance. Accordingly he ordered Jackson to sweep down the Shenandoah valley, threatening an advance upon Washington in its rear, thus putting the Federals there upon their defence. He rightly believed that the excessive concern felt at the North for the safety of the capital would make Jackson's operations an occasion of great alarm.

The result was precisely what Lee had intended. Jackson swept like a hurricane through the valley, moving so rapidly and appearing so suddenly at unexpected and widely separated points as to seem both ubiquitous and irresistible. The Federal army which was marching to reinforce McClellan was promptly turned aside and sent over the mountains to meet and check Jackson. While it was hurrying westward, Jackson suddenly slipped out of the valley and carried his "foot cavalry"—as his rapidly marching corps had come to be called—to the neighbourhood of Richmond, where Lee was ready to fall upon his adversary in full force, striking his right flank like a thunderbolt, pushing into his rear, pressing him back in successive encounters, threatening his base of supplies on the York River, and finally compelling him to retreat to the cover of his gunboats at Harrison's Landing on the James.

All this constituted what is known as the "Seven Days' Battles." It was a brilliant operation, attended at every step by heroic fighting on both sides, and by consummate skill on both—for if Lee's successful operation for his enemy's dislodgment was good strategy, McClellan's successful withdrawal of his army from its imperilled position to one in which it could not be assailed, was scarcely less so.

But still more dramatic events were to follow. McClellan had been driven away from the immediate neighbourhood of the Confederate capital, but his new position at Harrison's Landing was one from which he might at any moment advance again either upon Richmond or upon Petersburg, which was afterward proved to be the military key to the capital. His army was still numerically stronger than Lee's, and it might be reinforced at any time, and to any desired extent, while Lee had already under his command every man that could be spared from other points. More important still, the fighting strength of McClellan's forces had been bettered by the battling they had done. The men were inured to war work now, and had improved in steadiness and discipline under the tutelage of experience.

Except that its confidence in its general was somewhat impaired, the Army of the Potomac was a stronger and more trustworthy war implement than it had been at the beginning. So long as it should remain where it was, Lee must keep the greater part of his own force in the intrenchments in front of Richmond, and the seat of war must remain discouragingly near the Confederate capital. In the meanwhile a new Federal force, called the Army of Virginia, had been sent out from Washington under General John Pope, to assail Richmond from the north and west, while securely covering Washington. Pope's base was at Manassas, and his army had been pushed forward to the line of the Rappahannock, where there was no army to meet it and check its advance upon Richmond.