...dispatches: A battle has been raging furiously for the past two days on the Autistam Creek, a tortuous stream, having its source in the mountains and running down to the Potomac midway between Rohrersville and Sherpsburg. The rebels, cut off from the iron bridge at Harper's Ferry by the advance of General Franklin's corps, and fearing to cross the Potomac at any of the fords, with Gen. McClellan ...