Lee Permitted to Escape.

On Thursday night the sun went down with the opposing forces face to face, and their pickets within stone's throw of each other. On Friday morning the Rebel army was in Virginia, the National army in Maryland. Between dark and daylight, Lee evacuated the position, and carried his whole army across the river. He had no empty breastworks with which to endow us; but he left a field plowed with shot, watered with blood, and sown thick with dead. We found the débris of his late camps, two disabled pieces of artillery, a few hundred of his stragglers, two thousand of his wounded, and as many more of his unburied dead; but not a single field-piece or caisson, ambulance or wagon, not a tent, a box of stores, or a pound of ammunition. He carried with him the supplies gathered in Maryland and the rich spoils of Harper's Ferry.

It was a very bitter disappointment to the army and the country.

The John Brown Engine-House.

Bolivar Hights, Md., September 25, 1862.

Adieu to western Maryland, with the stanch loyalty of its suffering people! Adieu to Sharpsburg, which, cut to pieces by our own shot and shell as no other village in America ever was, gave us the warm welcome that comes from the heart! Adieu to the drenched field of Antietam, with its glorious Wednesday, writing for our army a record than which nothing brighter shines through history; with its fatal Thursday, permitting the clean, leisurely escape of the foe down into the valley, across the difficult ford, and up the Virginia Hights! Our army might have been driven back; it could never have been captured or cut to pieces. Failure was only repulse; success was crowning, decisive, final victory. The enemy saw this, and walked undisturbed out of the snare.

Three days ago, our army moved down the left bank of the Potomac, climbing the narrow, tortuous road that winds around the foot of the mountains; under Maryland Hights; across the long, crooked ford above the blackened timbers of the railroad bridge; then up among the long, bare, deserted walls of the ruined Government Armory, past the engine-house which Old John Brown made historic; up through the dingy, antique, oriental looking town of Harper's Ferry, sadly worn, almost washed away by the ebb and flow of war; up through the village of Bolivar to these Hights, where we pitched our tents.

Behind and below us rushed the gleaming river, till its dark, shining surface was broken by rocks. Across it came a line of our stragglers, wading to the knees with staggering steps. Beyond it, the broad forest-clad Maryland Hights rose gloomy and somber. Down behind me, to the river, winding across it like a slender S, then extending for half a mile on the other side, far up along the Maryland hill, stretched a division-train of snowy wagons, standing out in strong relief from the dark background of water and mountain.

Two weeks ago shots exchanged between the army of Slavery and the army of Freedom shrieked and screamed over the engine-house, where, for two days, Old John Brown held the State of Virginia at bay. A week ago its walls were again shaken by the thunders of cannonade, when the armies met in fruitless battle. Last night, within rifle-shot of it, the President's Proclamation of Emancipation was heard gladly among thirty thousand soldiers.