Arab Raid on Rome (846) and the Building of the Leonine Wall

The Arab raid on Rome in August 846 saw a Muslim fleet land at the mouth of the Tiber and plunder the great basilicas of St Peter and St Paul, which stood outside the city’s ancient walls. Rome itself held out, but the loss of treasures from the shrine of the apostles shocked Latin Christendom. In response Pope Leo IV built the Leonine Wall around the Vatican, creating the walled district known as the Leonine City.

Background

In the 9th century Muslim forces from North Africa were steadily conquering Byzantine Sicily, a campaign that began in 827 (see Muslim conquest of Sicily). Raiding fleets also operated along the coasts of mainland Italy, sometimes hired as allies by rival southern Italian rulers.

Rome was protected by the Aurelian Walls, built in the 270s. St Peter’s Basilica on the Vatican Hill and St Paul’s on the road to Ostia, however, lay outside them. These were the most important pilgrimage churches in the West and held great quantities of silver and gold given by emperors, kings and pilgrims.

The raid of 846

Around 23 August 846 a fleet landed near Ostia and Portus at the mouth of the Tiber. The Liber Pontificalis speaks of 73 ships, and the numbers of men and horses it gives are probably exaggerated; modern historians generally treat the force as a large raiding army of uncertain size. The defenders of the ports withdrew.

The raiders advanced along both banks of the Tiber. Local militia and the “scholae” of foreign residents near St Peter’s, including Saxons and Frisians, tried to resist but were defeated. The attackers then plundered St Peter’s and St Paul’s, stripping altars and fittings of precious metal. The gates of the city itself stayed closed and the Aurelian Walls were not breached.

Frankish forces sent by Emperor Lothair I under Guy I of Spoleto arrived and fought the raiders, with mixed results. The attackers withdrew south, some by land towards Gaeta and some by sea. Frankish annals report that part of the fleet was later lost in a storm.

Building the Leonine Wall

Pope Sergius II died in January 847, and his successor Leo IV (pope 847–855) made fortification a priority. With financial support from Lothair I, and labour drawn from the estates of the Church and towns of the region, work on a new wall around the Vatican began in 848.

The wall ran for roughly 3 kilometres, joining the Tiber near Castel Sant’Angelo (the ancient tomb of Hadrian) and enclosing St Peter’s and the surrounding quarter. It was strengthened with towers and gates. Leo IV consecrated the completed wall on 27 June 852, and the enclosed area became known as the “Civitas Leonina”, the Leonine City.

Leo also restored the damaged basilicas and fortified other sites, including a new settlement for refugees at Leopolis near Centumcellae (Civitavecchia).

The Battle of Ostia

In 849 a new Saracen fleet threatened Rome. Ships from Naples, Amalfi, Gaeta and Sorrento gathered at Ostia and, with Leo IV’s blessing, engaged the enemy. A storm scattered the attackers, and many prisoners were taken and, according to the Liber Pontificalis, put to work on the walls. Raphael’s workshop painted this “Battle of Ostia” in the Vatican Stanze in the 16th century.

Key people

Sergius II (pope 844–847) was in office during the raid. The papal biographies of the period present his reign unfavourably, and some later writers treated the disaster as a judgement on it, a view that reflects the politics of the sources rather than proven fact.

Leo IV (pope 847–855), a Roman by birth, is remembered above all as a builder and defender. Besides the wall, he restored churches damaged in 846 and organised the defence of the coast.

Lothair I, emperor and king of Italy, sent troops in 846 and contributed money for the fortifications, reflecting the Carolingian claim to protect the papacy.

Guy I of Spoleto, a Frankish duke in central Italy, led the relief forces that confronted the raiders after the plunder of the basilicas.

Legacy

The Leonine Wall gave the Vatican its first permanent defences. Later popes rebuilt and extended it; the raised passage known as the Passetto di Borgo, linking the Vatican to Castel Sant’Angelo, runs along a section of the wall. Stretches of the original fabric survive within Vatican City today.

Timeline

• 827: Muslim forces begin the conquest of Sicily.
• 846, c. 23 August: A Muslim fleet lands near Ostia and Portus.
• 846, late August: St Peter’s and St Paul’s outside the walls are plundered; Frankish troops intervene.
• 847, January: Pope Sergius II dies; Leo IV is elected.
• 848: Construction of the Leonine Wall begins.
• 849: An allied Italian fleet defeats a Saracen fleet at the Battle of Ostia.
• 852, 27 June: Leo IV consecrates the completed wall.

Why it matters

The raid of 846 showed that even the shrine of St Peter was exposed in an age of seaborne raiding. Leo IV’s answer, a wall around the Vatican, permanently changed the map of Rome and created the fortified core from which the later papal district, and ultimately Vatican City, grew.