For two weeks after the battle of Antietam, General McClellan kept his army camped on various parts of the field, and so far from exhibiting any disposition of advancing against the enemy in the Shenandoah valley, showed constant apprehension lest the enemy might come and attack him. On October 1, the President and several friends made a visit to Antietam, and during the three succeeding days reviewed the troops and went over the various battle-grounds in company with the general. The better insight which the President thus received of the nature and results of the late battle served only to deepen in his mind the conviction he had long entertained--how greatly McClellan's defects overbalanced his merits as a military leader; and his impatience found vent in a phrase of biting irony. In a morning walk with a friend, waving his arm toward the white tents of the great army, he asked: "Do you know what that is?" The friend, not catching the drift of his thought, said, "It is the Army of the Potomac, I suppose." "So it is called," responded the President, in a tone of suppressed indignation, "But that is a mistake. It is only McClellan's body-guard." At that time General McClellan commanded a total force of one hundred thousand men present for duty under his immediate eye, and seventy-three thousand present for duty under General Banks about Washington. It is, therefore, not to be wondered at that on October 6, the second day after Mr. Lincoln's return to Washington, the following telegram went to the general from Halleck: "I am instructed to telegraph you as follows: The President directs that you cross the Potomac and give battle to the enemy, or drive him south. Your army must move now while the roads are good. If you cross the river between the enemy and Washington, and cover the latter by your operation, you can be reinforced with thirty thousand men. If you move up the valley of the Shenandoah, not more than twelve thousand or fifteen thousand can be sent to you. The President advises the interior line, between Washington and the enemy, but does not order it. He is very desirous that your army move as soon as possible. You will immediately report what line you adopt, and when you intend to cross the river; also to what point the reinforcements are to be sent. It is necessary that the plan of your operations be positively determined on before orders are given for building bridges and repairing railroads. I am directed to add that the Secretary of War and the general-in-chief fully concur with the President in these instructions." This express order was reinforced by a long letter from the President, dated October 13, specifically pointing out the decided advantages McClellan possessed over the enemy, and suggesting a plan of campaign even to details, the importance and value of which was self-evident.