Leo IV was a 9th-century pope and bishop of Rome who led the Papal States from 847 until his death in 855. Born in Rome, he was educated at the monastery of St. Martin and served as a cardinal-priest before his unanimous election to the papacy. He is primarily remembered for his defensive efforts to protect the city from Saracen raids, including the construction of the Leonine Wall and the successful naval victory at the Battle of Ostia.
Defense of Rome
Following Arab raids on the city, Leo IV worked to repair damaged churches, including the restoration of St. Peter's Basilica. To secure the Vatican hill, he commissioned the construction of a defensive wall, creating an area known as the Leonine City. He also organized a maritime league of Italian cities, which successfully defeated a Saracen fleet at the Battle of Ostia in 849.
Veneration and legacy
Recognized as a saint, he is commemorated on July 17 in Catholic, Anglican, and Orthodox traditions. His leadership during the Middle Ages is famously depicted in a fresco by Raphael. While he was originally interred in St. Peter's Basilica, his remains were later moved to a tomb shared with other popes named Leo before being placed in a separate chapel during the 18th century.