 During July , two additional divisions were consolidated under Maj. Gen. Burnside 's command to form the IX Corps . At the beginning of August , Brig. Gen Jesse Reno assumed the command of the Corps and was ordered to support the advance of Maj. Gen. John Pope 's Army of Virginia towards Richmond . The 21st , along with the rest of the Corps , was quickly transported to Fredericksburg and then marched overland to join Pope 's forces on August 14 , 1862 , in the vicinity of Culpeper Court House , Virginia . 
