First Maryland Campaign. 105
the 14th Halleck says : " I fear you are exposing your left and rear." And even as late as the i6th he urges the same idea upon McClellan. Now, if we put together the condition of McClellan's army, his slowness and caution as a commander, which was so fully evidenced in the Peninsula campaign, and the apprehension with which the Federal Administration viewed his increasing distance from Wash- ington, is it not evident that McClellan's progress must have been slow, and as he approached the mountains slower still ? In estimating McClellan's progress. General Lee could not have known fully of Halleck's fears, and of the constant pulling back exercised upon Mc- Clellan from Washington, but he knew the sensitiveness of the Fed- eral Government in regard to that city, he knew McClellan's cautious character as a commander thoroughly, he knew the disordered con- dition of his army — indeed, probably underrated the rapidity with which it was recuperating — and from these data he estimated, fairly and justly, we believe, the length of time it would take McClellan to reach the South Mountain.
General Lee expected, of course, when he entered Maryland that the garrison at Harper's Ferry would leave the place and escape to the North. Finding that it continued there, he determined, while watching and waiting for McClellan, to capture this garrison and the large amount of ordnance and other supplies which had been col- lected at Harper's Ferry. He proposed to General Longstreet, it seems, to carry out this plan, but finding his senior lieutenant unable to appreciate the opportunity, he turned to Jackson, whose vigor and boldness better suited the enterprise.
On the loth of September the army left Frederick. Jackson, as General Longstreet states, was to make a sweeping march by way of Williamsport and Martinsburg, and, driving the Federal troops at the latter place towards Harper's Ferry, close all the avenues of escape in the angle between the Shenandoah and the Potomac. At the same time McLaws, with his own and Anderson's divisions, was sent into Pleasant Valley, with instructions to take Maryland Heights, and hedge in the garrison on the north side of the Potomac. J. G. Walker, with two brigades, was ordered from the mouth of the Monocacy to cross the Potomac, move towards Harper's Ferry, and, seizing the Loudoun Heights, to shut up the eastern angle formed by the Shenandoah and the Potomac. Longstreet was sent to Hagerstown to look after some supplies and reported movements of troops from Pennsylvania, while D. H. Hill was left at Boonesboro' to be ready to support Stuart's cavalry and to guard the mountain-