<Li> Maj. Gen. D.H. Hill (brigades of Brig . Gens . Roswell S. Ripley, Robert E. Rodes, Samuel Garland, Jr., George B. Anderson, and Col. Alfred H. Colquitt). </Li> <P> The remaining units were the Cavalry Corps, under Maj. Gen. J.E.B. Stuart, and the reserve artillery, commanded by Brig. Gen. William N. Pendleton . The Second Corps was organized with artillery attached to each division, in contrast to the First Corps, which reserved its artillery at the corps level . </P> <P> Near the town of Sharpsburg, Lee deployed his available forces behind Antietam Creek along a low ridge, starting on September 15 . While it was an effective defensive position, it was not an impregnable one . The terrain provided excellent cover for infantrymen, with rail and stone fences, outcroppings of limestone, and little hollows and swales . The creek to their front was only a minor barrier, ranging from 60 to 100 feet (18--30 m) in width, and was fordable in places and crossed by three stone bridges each a mile (1.5 km) apart . It was also a precarious position because the Confederate rear was blocked by the Potomac River and only a single crossing point, Boteler's Ford at Shepherdstown, was nearby should retreat be necessary . (The ford at Williamsport, Maryland, was 10 miles (16 km) northwest from Sharpsburg and had been used by Jackson in his march to Harpers Ferry . The disposition of Union forces during the battle made it impractical to consider retreating in that direction .) And on September 15, the force under Lee's immediate command consisted of no more than 18,000 men, only a third the size of the Federal army . </P> <P> The first two Union divisions arrived on the afternoon of September 15 and the bulk of the remainder of the army late that evening . Although an immediate Union attack on the morning of September 16 would have had an overwhelming advantage in numbers, McClellan's trademark caution and his belief that Lee had as many as 100,000 men at Sharpsburg caused him to delay his attack for a day . This gave the Confederates more time to prepare defensive positions and allowed Longstreet's corps to arrive from Hagerstown and Jackson's corps, minus A.P. Hill's division, to arrive from Harpers Ferry . Jackson defended the left (northern) flank, anchored on the Potomac, Longstreet the right (southern) flank, anchored on the Antietam, a line that was about 4 miles (6 km) long . (As the battle progressed and Lee shifted units, these corps boundaries overlapped considerably .) </P>

Where was the battle of antietam and who won