Army of Northern Virginia in motion late the evening of July 4 towards Fairfield and Chambersburg. Cavalry under Brig. Gen. John D. Imboden was entrusted to escort the miles-long wagon train of supplies and wounded men that Lee wanted to take back to Virginia with him, using the route through Cashtown and Hagerstown to Williamsport, Maryland. Thousands of more seriously wounded soldiers were left behind in the Gettysburg area, along with medical personnel. However, despite casualties of over 20,000 men, including a number of senior officers, the morale of Lee's army remained high and their respect for the commanding general was not diminished by their reverses. Unfortunately for the Confederate Army, however, once they reached the Potomac they found it difficult to cross. Torrential rains that started on July 4 flooded the river at Williamsport, making fording impossible. downstream at Falling Waters, Union cavalry destroyed Lee's lightly guarded pontoon bridge on July 4. The only way to cross the river was a small ferry at Williamsport. The Confederates could potentially have been trapped, forced to defend themselves against Meade with their backs to the river. The route of the bulk of Lee's army was through Fairfield and over Monterey Pass to Hagerstown. A small but important action that occurred while Pickett's Charge was still underway, the Battle of Fairfield, prevented the Union from blocking this route. Brig. Gen. Wesley Merritt's brigade departed from Emmitsburg with orders to strike the Confederate left and rear along Seminary Ridge. Merritt dispatched about 400 men from the 6th U.S. Cavalry to seize foraging wagons that had been reported in the area. Before they were able to reach the wagons, the 7th Virginia Cavalry, leading a column under Confederate Brig. Gen. William E. "Grumble" Jones, intercepted the regulars, but the U.S. cavalrymen repulsed the Virginians. Jones sent in the 6th Virginia Cavalry, which successfully charged and swarmed over the Union troopers. There were 242 Union casualties, primarily prisoners, and 44 casualties among the Confederates. Imboden's journey was one of extreme misery, conducted during the torrential rains that began on July 4, in which the 8,000 wounded men had to endure the weather and the rough roads in wagons without suspensions. The train was harassed throughout its march. At dawn on July 5, civilians in Greencastle ambushed the train with axes, attacking the wheels of the wagons, until they were driven off. That afternoon at Cunningham's