In AD 476, the last Roman Emperor gave up the throne to the Germanic General Odoacer, who maintained Roman customs to a great extent for the 13 years he ruled. He was forced to abdicate when the Ostrogoths, an East Germanic tribe and a branch of the Goths, conquered Rome and all of Italy, which helped spark the Gothic War (AD 535–554). Rome’s infrastructure was ruined, which allowed more barbarous Germanic tribes, like the Lombards, attack and later gain control of Italy.

Consequently, the Lombards founded a kingdom in the north of Italy. The Lombards dominated with military might, took Ravenna and abolished its exarchate (governor). In turn, the popes asked the Franks for help. The Franks defeated the Lombards and paved the way to the popes’ strong position on the peninsula, as well as the creation of Papal States.

The 11th Century was the worst period in the Middle Ages for Rome. Later, however, trade began to slowly increase and the economy picked up. The popes regained their power and began a long war with the empire. In the 12th Century, some of the Italian cities within the Holy Roman Empire began to rebel, demanding autonomy. Consequently, Northern Italy established independent city-states, retaining this status until as late as the 19th Century.

In the beginning of the 12th Century, the Byzantine Emperor Manuel I Komnenos attempted to conquer Southern Italy. In 1155, the emperor convinced generals Michael Palaiologos and John Doukas with Byzantine armed forces and large amounts of gold to (unsuccessfully) invade Apulia. By the end of 12th Century, the Byzantine army had left Italy, with only a few permanently gained territories.

In the 11th Century, Norman tribes occupied the newly acquired territories of Lombard and Byzantine, south of Italy, thus ceasing a 600-year-old presence of both military forces on the peninsula. The autonomous city-states were also subjugated. During this century, the Normans also expelled the Muslims from Sicily. Wanting to prove its authority in Southern Italy, Byzantium sought revenge against Norman rule.

The city of Bari, a capital city in Southern Italy, left its gates open to the emperor’s army and the joyful citizens demolished the Norman citadel, as a symbol of the oppression by the Normans. In turn, Manuel longed for restitution of the Roman Empire through a union of the Orthodox and Catholic Churches, and a coalition was established between Manuel and Pope Adrian IV.