The first encounter, a double one, took place on September 14th, at two passes of South Mountain, a continuation of the Blue Ridge, north of the Potomac. General Franklin, who had been sent to relieve Harper's Ferry, met a Confederate force at Crampton's Gap and defeated it in a sharp battle of three hours' duration. Meanwhile, the First and Ninth Army Corps, under Burnside, encountered a stronger force at Turner's Gap seven miles farther up. The battle here continued many hours, till late in the night, and the Union troops were victorious. General Reno was killed. Lee's loss was nearly twenty-seven hundred, of whom eight hundred were prisoners. The Federals lost twenty-one hundred men and they failed to save Harper's Ferry. Lee now placed Longstreet and D. H. Hill in a strong position near Keedysville, but learning that McClellan was advancing rapidly, the Confederate leader decided to retire to Sharpsburg, where he could be more easily joined by Jackson. September 16th was a day of intense anxiety and unrest in the valley of the Antietam. The people who had lived in the farmhouses that dotted the golden autumn landscape in this hitherto quiet community had now abandoned their homes and given place to the armed forces. It was a day of marshaling and maneuvering of the gathering thousands, preparatory to the mighty conflict that was clearly seen to be inevitable. Lee had taken a strong position on the west bank of Antietam Creek a few miles from where it flows into the Potomac. He made a display of force, exposing his men to the fire of the Federal artillery, his object being to await the coming of Jackson's command from Harper's Ferry. It is true that Jackson himself had arrived, but his men were weary with marching and, moreover, a large portion of his troops under A. P. Hill and McLaws had not yet reached the field. McClellan spent the day arranging his corps and giving directions for planting batteries. With a few companions he rode along the whole front, frequently drawing the fire of the Confederate batteries and thus revealing their location. The right wing of his army, the corps of Generals Hooker, Mansfield, and Sumner, lay to the north, near the village of Keedysville. General Porter with two divisions of the Fifth Corps occupied the center and Burnside was on the left of the Union lines. Back of McClellan's lines was a ridge on which was a signal station commanding a view of the entire field. Late on the afternoon of the 16th, Hooker crossing the Antietam, advanced against Hood's division on the Confederate left. For several hours there was heavy skirmishing, which closed with the coming of darkness. The two great armies now lay facing each other in a grand double line three miles in length. At one point (the Union right and the Confederate left) they were so near together that the pickets could hear each other's tread. It required no prophet to foretell what would happen on the morrow.