In fact, its elevated position over the town of Cassino was an important military point, also in view of the ascent to the Monastery. 

During the third battle, known as Dickens Operation, Rocca Janula, located 195 above seal level, was defended by German paratroopers, but on the afternoon of 15 March 1944, the day of the total bombardment of the town, it was taken by New Zealand Soldiers in a coup d'état. Several German paratroopers were imprisoned. Another important episode took place on 19 March 1944 when the Germans, with the pioneer battalion of the 1st Parachute Division, fiercely counter-attacked the castle to regain possession. The 4th Battalion of the Essex Regiment was there to defend. After a morning of fighting, with heavy losses on both sides, the castle remained in Allied hands. A well-known cease-fire was observed in the afternoon to gather the dead and wounded on the battlefield.

A monument at the entrance to the castle is dedicated to the British 4th Essex Battalion, which stood out for its valour and suffered heavy losses in that battle.

Although in ruins for years, the fortress underwent extensive restoration in the 2000s and was reopened to the public on 25 September 2015. Today it is open to visitors and hosts exhibitions and cultural events. Currently run by a cooperative, it has an entrance fee of €3. The price is increased in case of guided tours.