In December, most of the 1st Airborne Division (minus the 2nd Parachute Brigade) returned to England, and began training and preparing for the Allied invasion of Normandy. It was not involved in the Normandy landings in June 1944, being held in reserve. In September 1944 the 1st Airborne took part in Operation Market Garden. The division, with the Polish 1st Parachute Brigade temporarily attached, landed behind German lines, to capture crossings on the River Rhine, and fought in the Battle of Arnhem. After failing to achieve its objectives, the division was surrounded and took very heavy casualties, but held out for nine days before the survivors were evacuated.