 Complete the following phrase:  As a part of the Army of the Potomac, it was initially assigned to the defenses of Washington, D.C. Later, the 68th was transferred to the Shedoah Valley and fought at the Battle of Cross Keys. The men of the 68th were then reassigned to central Virginia and found themselves in the thick of the fighting at Second Bull Run. After returning to the nations capital, the regiment fought in Chancellorsville and was routed by Confederate forces. At 