In early 1944, two Allied armies were poised to launch a massive assault against German forces in central Italy to open the way north to Rome. Obstructing them was the Gustav Line: the most formidably constructed defensive line the Western Allies would ever come up against. There were three routes of attack to choose from. The fastest one passed directly through the Liri valley, but it demanded the perilous fording of the Rapido River. The second possible route involved outflanking the Gustav Line to the east, but to do so the Allies would need to capture innumerable rough peaks and ridges along the massif on terrain that favoured the defenders. The third and final option was to breach the enemy's defences directly in front of the town of Cassino, crowned with its iconic medieval monastery; it would mean engaging in costly house-to-house fighting until the very last of the determined German paratroopers had been killed or captured. The Allied commanders decided to try all three options. None of them were easy, and all proved deadly.