...d he must be forced back from the Potomac before the road could be repaired and reopened. To effect this Banks marched, February 22d, from his winter camp at Frederick, Md., and his advance entered Harper's Ferry the 24th, and laid a bateau bridge across the Potomac on which two brigades crossed on the 26th and occupied the town. McClellan himself reached that place the same day and ordered the establishmen...