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With the coming dawn of the eighteenth came confirmation of the cheering rumors of the night before: that Antietam was over, the battle won, the invasion a failure, and that the enemy as in haste to put the Potomac between himself and his adversary. Then the regiment retraced its steps to Funkstown, a distance of about seven miles, where it was halted, reviewed by the colonel [Col. Kneass] camp lines designated, streets laid out, and every preparation made for a well-organized stop. But it was not so to be. Stuart, the famous Confederate cavalry leader, was still abroad on our side of the Potomac. There was a bit of a flurry about Williamsport. Again there was a toilsome hurried march over the old route as far as Hagerstown, and then well out the Clear Spring Road in the direction of Williamsport, where most of the flurry was. At Hagerstown "the hasty loading of trains, locomotives with steam up, and many anxious faces told of danger to the town, which happily General Reynolds and his division averted." All night on this the night of the eighteenth out on the Clear Spring road, with one or two companies detailed for picket, the regiment was in line of battle, "every man at his post," silently awaiting, with loaded musket well in hand, an enemy that never appeared, listening for sounds that were never heard. It seems to be conceded that this large gathering of militia at this point came under Stuart's observation, and diverted a movement which, though only intended as a raid, would, if successful, have been fraught with serious consequences.
Latta, James. History of the First Regiment Infantry National Guard of Pennsylvania (Gray Reserves) 1861-1911. Philadelphia: J.B. Lippincott Co., 1912.