Operation Pegasus launched Operation Market Garden, an attempt by the British 2nd Army to bypass the Siegfried Line and advance into the Ruhr, Germany’s industrial heartland. The operation required the First Allied Airborne Army to seize several bridges over rivers and canals in the Netherlands, allowing ground forces to advance and cross the Lower Rhine at Arnhem. The 1st British Airborne Division dropped onto Arnhem on 17 September. They encountered far greater resistance than had been expected and only a small force were able to reach Arnhem road bridge. XXX Corps ground advance became delayed and without reinforcement this small force under
First Allied Airborne Army when a major offensive was launched by the Germans on the orders of Adolf Hitler; on 16 December 1944 Operation ""Watch on the Rhine" began, with three German armies attacking through the Ardennes, hundreds of thousands of German troops and tanks breaking through Allied line on the American sector. The operation took the Allied forces completely by surprise, and several units under the command of First Allied Airborne Army became involved in the Allied attempt to first halt, and then repel the offensive; these units were principally the 101st Airborne Division, 82nd Airborne Division and the 6th Airborne Division. With