The abbey of Monte Cassino is one of the two largest monasteries in Italy. The abbey was founded by Saint Benedict in the 6th century. The abbey made up one section of the 161 km long German Gustav Line, intended to block the Allied advance into Italy. Between 17 January and 18 May 1944, Monte Cassino was the scene of fierce fighting. Lying in a protected historic zone, the abbey itself had been left unoccupied by the Germans. Unfortunately, the Allied commanders believed that the abbey was being used as an artillery observation point by the German forces. In spite of a lack of clear evidence, the monastery was marked for destruction. On 15 February American bombers dropped their bombs on the abbey, reducing the entire top of Monte Cassino to a smoking mass of rubble. The destruction of the abbey was one of the greatest military blunders of the Second World War. 230 Italian civilians that were seeking refuge in the monastery were killed and with the building now destroyed German paratroopers occupied the ruins, which provided them with excellent defensive cover. Fortunately, the destruction was not complete. At the beginning of the battle German officers had transferred some 1,400 precious manuscripts and other items from the abbey to the Vatican saving them from destruction.
The first Allied soldiers who reached the ruins of Monte Cassino on 18 May 1944 were Polish soldiers of the 1st squadron, 12 Podolski Lancers Regiment.
After the war the abbey was rebuilt exactly as it was.