The September day wore on.  The country between the South Mountain and Sharpsburg, resembling in every characteristic the Valley of the Shenandoah, is open and gently undulating.  No leagues of woodland, as in Eastern Virginia, block the view.  The roads run through wide cornfields and rolling pastures, and scattered copses are the only relics of the forest.  It was not yet noon when the Federal scouts appeared among the trees which crown the left bank of the Antietam Creek.  “The number increased, and larger and larger grew the field of blue until it seemed to stretch as far as the eye could see.  It was an awe-inspiring spectacle,” adds Longstreet, “as this grand force settled down in sight of the Confederates, shattered by battles and scattered by long and tedious marches."* (* Battles and Leaders volume 2 page 667.) But when night fell upon the field the only interchange of hostilities had been a brief engagement of artillery.  McClellan’s advance, owing to the difficulty of passing his great army through the mountains, and to the scarcity of roads, had been slow and tedious; in some of the divisions there had been unnecessary delay; and Lee had so disposed his force that the Federal commander, unenlightened as to the real strength of his adversary, believed that he was opposed by 50,000 men.

September 16.

Nor was the next morning marked by any increase of activity.  McClellan, although he should have been well aware that a great part of the Confederate army was still west of the Potomac, made no attack.  “It was discovered,” he reports, “that the enemy had changed the position of some of his batteries.  The masses of his troops, however, were still concealed behind the opposite heights.  It was afternoon before I could move the troops to their positions for attack, being compelled to spend the morning in reconnoitring the new position taken up by the enemy, examining the ground, and finding fords, clearing the approaches, and hurrying up the ammunition and supply trains."* (* O.R. volume 19 part 1 page 55.)

Considering that McClellan had been in possession of the left bank of the Antietam since the forenoon of the previous day, all these preliminaries might well have been completed before daylight on the 16th.  That a change in the dispositions of a few batteries, a change so unimportant as to pass unnoticed in the Confederate reports, should have imposed a delay, when every moment was precious, of many hours, proves that Lee’s and Jackson’s estimate of their opponent’s character was absolutely correct.  While McClellan was reconnoitring, and the guns were thundering across the Antietam, Jackson and Walker crossed the Potomac, and reported to Lee in Sharpsburg.* (* According to Jackson’s staff officers he himself reported shortly after daylight.) Walker had expected to find the Commander-in-Chief anxious and careworn.  “Anxious no doubt he was; but there was nothing in his look or manner to indicate it.  On the contrary, he was calm, dignified,