Feast Day : July 17
Leo was born into a Lombard family in Rome. He studied at Saint Martin’s monastery in that city and became a Benedictine monk. He was made subdeacon of the Lateran Basilica by Pope Gregory IV (r. 827–844) and soon thereafter was named cardinal-priest of the church of the Quatuor Coronati by Pope Sergius II (r. 844–847). He was unanimously elected to the Chair of St. Peter to succeed Sergius and was consecrated on April 10, 847. One of Leo’s first official actions was to repair the walls of Rome, which had been destroyed in the Saracen attack of the previous year. He also solicited the help of the Holy Roman Emperor, and of all the cities and agricultural colonies of the duchy of Rome, to build a wall around the Vatican, a project that required four years to complete. The newly fortified area became known as the Leonine City in his honor. In addition to these fortifications, Leo also restored many Roman churches, including parts of St. Peter’s Basilica, which had suffered especially heavy damage. The list of his benefactions to churches takes up 28 pages in the Liber pontificalis. In 849, Leo entered into an alliance with several Greek cities. Thanks to his prayers and exhortations to the soldiers and sailors, and to a fierce storm at sea, the alliance soundly defeated the Moslem Saracens at the Roman port of Ostia. The latter part of Leo’s reign was largely concerned with enforcing Church discipline. He died in the midst of these endeavors and was buried in St. Peter’s on July 17, 855. He is credited with miracles and his name appears in the Roman Martyrology.