The Lost Dispatch, or the Story of Antietam.

Sanders was unusually well filled last evening to hear Colonel Allan's lecture on the Battle of Antietam. The outline of what he said is briefly as follows:

On September 2nd, 1862, Lee was within a few miles of Washington where McClellan was quartered with the Union army. Lee formed a plan to invade Maryland, and thus draw McClellan away from Washington, his base of supplies. Accordingly Lee crossed the upper Potomac and concentrated at Frederick City. McClellan then marched slowly toward him. Meanwhile Lee sent several detachments to capture a garrison of about 11,000 men at Harper's Ferry; but kept most of his men strung along the Blue Ridge.

Unfortunately, McClellan got hold of Lee's despatch and on September 10, acting on his information, marched against the part of Lee's army above Harper's Ferry. But Lee held him off until the 15th, when Jackson captured Harper's Ferry with its garrison, artillery and small arms.

Then Lee fell a few miles back, and drew up to the north and east of Sharpsburg, where all his troops, except Hill's division, joined him. The Union forces were drawn up against him; and both sides fought fiercely during the seventeenth. Both parties were exhausted, and the Confederates began to draw in their lines. Then Sedgwick's fresh division of 6000 northern men made a charge. But at that moment Hill came up with his soldiers from Harper's Ferry, charged Sedgwick in the flank, and in twenty minutes routed the whole division. Then Burnside's troops drove up the southern wing of the Confederates. But Hill's division drove Burnside back, completely shattered.

At nightfall then Lee held the same ground; although both sides were exhausted. McClellan was too much disorganized to attack the next day, and accordingly he waited for reinforcements. But meanwhile Lee fell back across the Potomac. McClellan's fault was not failure to attack again, but to attack one day earlier, while one-third of Lee's forces were at Harper's Ferry.