Fitz John Porter
While skirmishing occurred all along the line between the armies, McClellan heard a rumor from a Virginia civilian that a Confederate force of 17,000 was moving to Hanover Court House, north of Mechanicsville. If this were true, it would threaten the army's right flank and complicate the arrival of McDowell's reinforcements. A Union cavalry reconnaissance adjusted the estimate of the enemy strength to be 6,000, but it was still cause for concern. McClellan ordered his close friend, Maj. Gen. Fitz John Porter, commander of the newly formed V Corps, to deal with the threat.