Winchester is not a place of any strategic importance; nor is it easily to be held against a greatly superior force. It is approachable on all sides by numerous roads, without any difficulty of intercommunication. But there are some strong positions near the place susceptible of fortification; and several of these had been very skilfully improved by General Milroy, during his occupation of the post--not with any view, however, of attempting to hold it, in case of an attack by overwhelming numbers, but to resist any sudden concentration of the forces which were known to be in the valley or likely to invade it. These fortifications would have successfully resisted Stuart's cavalry, with all the field artillery he could have brought against them. On Saturday, the 13th of June, the enemy was encountered early in the day within a short distance of Winchester; but no enemy appeared in the direction of the Strasburg road until the afternoon. Our forces held both roads, but they gradually withdrew, skirmishing, during the day, as the enemy steadily approached the town. At about 6 o'clock in the afternoon, a prisoner was captured, who professed to belong to Hay's Louisiana brigade, of Ewell's rebel corps. From this prisoner was derived the information that both Ewell and Longstreet, with their entire forces, fifty thousand strong, were in the immediate vicinity of Winchester. This report was soon fully confirmed by a deserter, who shortly afterward entered our lines; and now, for the first time, it was rendered certain that the command at Winchester was in the immediate presence of an overwhelming force, probably the advance of Lee's entire army. At this time the 3d brigade, under Colonel McReynolds, was on the march from Berryville to Winchester, in pursuance of the signal, which had been given early in the morning. The direct road from Berryville to Winchester was only ten miles; but the appearance of the enemy at Berryville prevented Colonel McReynolds from taking that route. He accordingly pursued the Harper's Ferry road for a short distance, then turning to the left by a circuitous road through Summit Point to Winchester. His rear guard was attacked by the enemy's cavalry before leaving Berryville, and also again with greater violence at the Opequan Creek, between Summit Point and the Martinsburg road. The enemy was handsomely repulsed in both instances, but particularly in the latter, when the cavalry, under Major A. W. Adams, and the artillery, commanded by Captain Alexander, were both brought into action. After a march of thirty miles, the 3d brigade reached the forts at Winchester about ten o'clock at night. After it became known what force was in front of Winchester, early in the night of Saturday, under cover of the darkness, the men were withdrawn from the Front Royal and Strasburg roads, and posted in the southern part of the town, with orders to retire to the forts at two o'clock in the morning.