During the Battle of Monte Cassino in the Italian Campaign of World War II (January–May 1944) the Abbey was heavily damaged. The German military forces had established the 161-kilometre (100-mile) Gustav Line, in order to prevent Allied troops from advancing northwards. The abbey itself however, was not initially utilised by the German troops as part of their fortifications, owing to General Kesselring's regard for the historical monument. The Gustav Line stretched from the Tyrrhenian to the Adriatic coast in the east, with Monte Cassino itself overlooking Highway 6 and blocking the path to Rome. On 15 February 1944 the abbey was almost completely destroyed in a series of heavy American-led air raids. The Commander-in-Chief Allied Armies in Italy, General Sir Harold Alexander of the British army ordered the bombing. The bombing was conducted because many reports from the British commanders of the Indian troops on the ground suggested that Germans were occupying the monastery, and it was considered a key observational post by all those who were fighting in the field. However, during the bombing no Germans were present in the abbey. Subsequent investigations found that the only people killed in the monastery by the bombing were 230 Italian civilians seeking refuge there. Following the bombing the ruins of the monastery were occupied by German Fallschirmjäger(paratroopers) of the 1st Parachute Division, because the ruins provided excellent defensive cover.