On September 13, Special Order 191 fell into the hands of two Union soldiers, providing McClellan with Lee's battle plans, and giving him the confidence he needed to plan an offensive for the following day. William B. Franklin led the attack at Crampton's Gap and Parham was sent with two regiments from Mahone's Brigade to hold a defensive line, with the 41st Virginia in reserve. Franklin broke Parham's line about 5:00 pm, and reinforcements from the 41st and another brigade sent to help delayed him long enough that he did not move through the gap before night fell. Franklin decided not to attempt to drive them on September 15, and, after dark, the 41st crossed the Potomac on a pontoon bridge and spent the night in Halltown, Virginia, before moving to the fighting at Sharpsburg, Maryland.