In June 1944 the Allies invaded Normandy and advanced in a broad front as far as Antwerp. The rapid advance came to a halt when supplies became overstretched and it faced newly regrouped German lines.British Field Marshal Montgomery devised a plan to invade Germany north of these lines: Operation Market Garden.The plan consisted of two parts.Operation Market: airborne troops capturing the river crossings along the route.Operation Garden: ground troops advancing northwards.The First British Airborne Division was ordered to take the bridges at Arnhem. They then had to hold the bridges for two days until the tanks of theXXX Corps (30th Corps) arrived heading north.