The Battle of Monte Cassino took place from 17 January 1944 to 18 May 1944. It was a series of four offensives carried out by Allied troops in central Italy (who was a key ally of Germany) in an attempt to breakthrough the Winter Line and occupy Rome.

Operation Diadem, also referred to as the Fourth Battle of Monte Cassino or, in Canada, the Battle of the Liri Valley, was an offensive operation undertaken by the Allies of World War II (U.S. Fifth Army and British Eighth Army) in May 1944, as part of the Italian Campaign of World War II.