The Battle of Monte Cassino was a series of four major Allied assaults against German defensive positions in Italy between January and May 1944 during the Second World War. The Germans had built the Gustav Line across central Italy, with Monte Cassino — a mountain crowned by a historic monastery — forming a key strongpoint. Allied forces, including British, American, Polish, French and New Zealand troops, attempted repeatedly to break through the line to open the road to Rome. After heavy fighting and widespread destruction, including the controversial bombing of the monastery, Polish forces finally captured the heights in May 1944. The victory allowed the Allies to advance northwards and eventually liberate Rome.