In September 1943, a three hundred thousand strong Allied army invaded Italy; they aimed to undermine Hitler's control of what Winston Churchill called the "underbelly of Europe." Although Mussolini's fascist government surrendered on 8 September 1943, Germany’s much feared paratroops remained to defend the country. At Monte Cassino, an industrial town sixty miles south of Rome, the forces of General Harold Alexander faced the frantic defenders of Hitler's Reich in a series of bloody and controversial battles.

The sixth century Benedictine monastery of Monte Cassino towered over the battleground, and was of great strategic importance. Precariously perched atop a seventeen hundred foot high mountain, it housed one of the greatest collections of medieval manuscripts in the world and had been an important centre of pilgrimage for many years.

During the battle, this splendid structure became the focal point of a formidable German defensive network called the Gustav Line. In order to progress and reach Rome, Allied forces knew they had to obliterate the Gustav Line, transforming the abbey into a notorious casualty of war.

Over an intense six month period, four separate battles eventually resulted in the conquest of Monte Cassino and the destruction of the Gustav Line. On the rocky slopes of southern Italy, in horrific weather conditions, over a hundred thousand Allied troops were killed or wounded.

In this groundbreaking documentary, we examine photographs taken by the reconnaissance aircraft that flew high above the carnage capturing the vicissitudes of the battle. British and German aerial photographs taken at the time have been layered over a three dimensional contour map in order to create a CGI model of the battles for Monte Cassino.

For the first time, these original high-resolution images allow the viewer to track the battle, step by step, from the air. Using cutting edge technology, unique archive film, re-enactments and extraordinary interviews with the men who were there, this documentary provides a unique and refreshing insight into the complex killing grounds of Monte Cassino.