 The main targets were rail yards, bridges, and communication centers, with a secondary focus on fuel processing and storage facilities and other important industrial sites.During the three days leading up to Montgomery's attack, targets in front of the 21st Army Group zone and in the Ruhr area to the southeast were pummeled by about 11,000 sorties, effectively sealing off the Ruhr while easing the burden on Montgomery's assault forces.Montgomery had originally planned to attach one corps of the U.S. 9th Army to the British 2nd Army, which would use only two of the corps′ divisions for the initial assault.