In World War II, after southern Italy was invaded by the Allies, the Germans entrenched around the German Gustav Line, which, in its southern tip, was anchored around the mountains behind Cassino. The town was therefore the site of fierce fighting in the Battles of Monte Cassino. On 15 February 1944 the Abbey was destroyed by a heavy aerial bombardment. The Allies, believing that the Abbey was a strategic position occupied by the Germans, bombed it, killing many of the people who had taken refuge. The works of art contained in the Abbey were transferred to Rome by the Germans before the bombing, but many disappeared on the way. On 15 March, the town was completely razed to the ground by aerial bombardment and artillery fire, followed by an unsuccessful Allied attack. 2,026 civilians, one-tenth of the town's entire population of 20,000, were killed by the bombing and fighting before and during the battles of Cassino.