At the end of World War II, dozens of Allies were killed by snipers from the peak of Monte Cassino. Each ground attack of the Allies failed. Eventually the Allies decided to drop 1400 tons of bombs on the monastery. The abbey founded in 529 by Saint Benedict was completely destroyed. Beautiful wall paintings and numerous works of art were lost. Afterwards it appeared that the Germans were not within the walls of the monastery but positioned around the monastery. The battle of Monte Cassino continued from January 15 to May 18, 1944.
Source: Noah Charney, 2010, Het Lam Gods. 's Werelds meest begeerde meesterwerk.