 When the I Corps arrived around midnight, it moved to bolster the right and anchored the army's flank on the Rapidan River.The 151st Pennsylvania was posted abutting the river and was tasked with guarding the main Federal supply and retreat route at United States Ford.The I Corps remained mostly unengaged for the remainder of the battle, however the 151st Pennsylvania worked in conjunction with the nearby 12th Massachusetts to fight off a series of small incursions by Brig.