Daniel Harvey Hill
The day after the battle of Oak Grove, the right flank of the Army, located north of the Chikahominy River, was attacked by forces from General Daniel Harvey Hill. The right flank, made up of 5th Corps under command of General Fitz-John Porter, broke during an attack on the 27th of June due to lack of support and retreated across the Chikahominy towards the main battle force on the southern side of the Chikahominy. It was at this point that McClellan believed it best to retreat back to the James River.