As Lee’s men approached from Boonsboro during the morning hours of September 15, they turned left and right off the pike to form their lines on Sharpsburg Ridge. Brig. Gen. John Hood, with only two brigades, held the ground at the fringe of the West Woods—from the Dunker Church northwest to Nicodemus Hill near the Potomac. Here, Stuart’s cavalry protected the left end or flank of the line. From Hood’s position southward to Sharpsburg, D. H. Hill placed his five brigades east of and paralleling the Hagerstown Pike. Brig. Gen. Nathan Evan’s brigade occupied the center of the line in front of Sharpsburg; his men straddled the Boonsboro Pike. The six brigades of Maj. Gen. D. R. Jones extended the Confederate front southeast nearly a mile to the Lower Bridge over Antietam Creek. The fords over the Antietam at the extreme right of the line were guarded by Col. Thomas Munford’s cavalry brigade. Artillery was placed at vantage points on the ridges. Throughout the 15th, Lee presented a show of strength with 14 brigades of infantry and 3 of cavalry—about 18,000 men. [Illustration: _Army supply train crosses Middle Bridge over Antietam Creek. After ascent of ridge in background, Boonsboro Pike dips into a ravine, then ascends Sharpsburg Ridge and enters the village._ Courtesy, National Archives.] _McClellan Concentrates at the Antietam_ Against this pretense of power, General McClellan marched cautiously on the forenoon of the 15th, over good roads and in fine weather. By noon, he arrived at the Confederate front with a force of nearly 75,000 men. McClellan hesitated, and the day wore away. As the early morning fog of the 16th cleared, Lee’s artillerists caught sight of Federal guns on the high bank beyond Antietam Creek. The thunder of a prolonged duel between Lee’s guns and Brig. Gen. Henry Hunt’s powerful Federal batteries soon rolled through the hills. There was no question in McClellan’s mind now that Lee intended to hold Sharpsburg Ridge. In midafternoon of the 16th, McClellan prepared for battle. Maj. Gen. Joseph Hooker’s I Corps was instructed to take position opposite the Confederate left on the Hagerstown Pike. Maj. Gen. Joseph Mansfield’s XII Corps and Maj. Gen. Edwin Sumner’s II Corps were to extend the battleline from Hooker’s left to the Smoketown Road and on to Antietam Creek near Pry’s Mill Ford. The V Corps, Maj. Gen. Fitz-John Porter commanding, was directed to occupy the center of the Federal line on the Boonsboro Pike. Burnside was to place his IX Corps just east of the Lower Bridge over Antietam Creek. Maj. Gen. William Franklin’s VI Corps was to support the entire front. In the center, on the high east bank of Antietam Creek, and south of the Boonsboro Pike, General Hunt placed four batteries of 20-pounder Parrott rifles, the most powerful cannon on the field.