...heavy rains followed that of Gettysburg, swelling all the tributaries of the Potomac, making that stream impassable at the Williamsport ford, and endangering Lee's pontoon bridge at Falling Waters. Imboden , withdrawing from the Cumberland valley, covered with intrenchments Lee's trains concentrated at Williamsport, manned his works with several batteries of artillery, and stood ready to repulse any cav...