During World War II, Operation Diadem was the 1944 Allied spring ground offensive in Italy launched on 12 May, 1944 to turn the German defenses at Cassino and open up the Liri Valley.
During World War II, Operation Diadem was the 1944 Allied spring ground offensive in Italy, part of the Allied invasion of Italy. It was launched on 12 May, 1944 to turn the German defenses at Monte Cassino on the Winter Line and open up the Liri Valley.