St. Leo IV

Leo IV became pope in 847, just a year after Saracen raiders had sacked St. Peter's Basilica and plundered the tombs of the apostles. He immediately set about fortifying the Vatican district, building massive walls that still partially stand and bear his name: the Leonine Walls. In 849, he organized a naval league of Italian coastal cities that confronted the Saracen fleet at the Battle of Ostia. A providential storm scattered the enemy ships, and the Christians won decisively. Leo used the captured raiders to help rebuild Rome's walls. He also held a synod in 853 that addressed clerical reform.