LONDON, May 10 -- Fifty years ago Wednesday, Allied soldiers involved in the Italian campaign launched Operation Diadem, the fourth and biggest offensive to break the heavily fortified Gustav line south of Rome.
At 11 p.m., the U.S. 5th and the British 8th armies, under the command of the British Field Marshal Harold Alexander, opened fire on a front stretching from the Cassino area to the Adriatic coast. Heavy bombers pounded German lines, and 45 minutes later British, American, Indian, French, Polish and Moroccan troops launched an infantry attack.
Although the Allies had an important numerical superiority, it would take them until May 18 to capture the ruins of the Cassino monastery, destroyed during a controversial Allied bombing raid earlier that year.
The forcing of the Gustav line helped ease the pressure on the Anzio beachhead, enabling 150,000 trapped Allied soldiers to break out of the position and link up with the main body of troops battling their way up the peninsula. May 25, the roads were open to Rome and less than two weeks later the city had fallen to the Allies.
The German 10th Army, under the command of Field Marshal Albert Kesselring, withdrew to the defensive Gustav Line at the start of the winter of 1943-44 and the position was intended to stop, not just slow, the Allied advance.
The line, dominated by a monastery settled on the top of Monte Cassino, was fortified with gun pits, concrete bunkers, turreted machine-gun emplacements, barbed wire and minefields.
Several attempts to breach the front had been made in the beginning of 1944, but all had failed, costing the Allies heavy losses.
The best-known of these unsuccessful attempts was an offensive combining an amphibious end-run operation at Anzio, north of the Gustav Line, with a direct assault on the German defensive position. The attack aimed to breakthrough at Anzio and open a route to Rome, but the Allied forces failed to take advantage of the Anzio beachhead and were unable to resist a German counter-attack.
The successive failures had brought the military commanders under a lot of pressure and Operation Diadem was their last opportunity to breach the Gustav Line. American military chiefs would have prefered to limit operations on the Italian front and proceed, instead, to a diversionary landing in the south of France in support of the D-Day invasion.
Elsewhere on May 11 50 years ago, Marauder and Havoc warplanes of the U.S. 9th Air Force began a series or raids around the beaches chosen for the Normandy invasion, striking at airfields at Beaumont-le-Roger and Cormeilles-en-Vex, near Caen in Normandy.
The Allied command was hoping that the attacks would force the German air forces to fight on D-Day from bases as far removed as possible from the battlefield.
Invasion fever intensified in Axis-held countries. The Germans were reinforcing defenses on the Norwegian coast, building new bases and installing anti-submarine nets in the country's main ports.
The Germans were expecting diversionary Allied landings in Norway during the coming invasion of western Europe.