Fall of Aghlabid
The Muslims of southern Italy had reached to Rome, which was like the Makkah for the Christians. But the Muslims moved back down south, instead of continuing to go up. This had a deep effect on the Christians, during the Crusades the Normandies had sandwiched the Muslims, and forced the Muslims to build a wall around the Vatican, because they were terrified that the Muslims would be able to conquer them again.