Confederate supplies and thousands of wounded men proceeded over South Mountain through Cashtown in a wagon train that extended for 15-20 miles, enduring harsh weather, treacherous roads, and enemy cavalry raids. The bulk of Lee's infantry departed through Fairfield and through the Monterey Pass toward Hagerstown, Maryland. Reaching the Potomac, they found that rising waters and destroyed pontoon bridges prevented their immediate crossing. Erecting substantial defensive works, they awaited the arrival of the Union army, which had been pursuing over longer roads more to the south of Lee's route. Before Meade could perform adequate reconnaissance and attack the Confederate fortifications, Lee's army escaped across fords and a hastily rebuilt bridge.