The emperor and the pope also came into conflict over Sicily and southern Italy, disputes that eventually involved the kings of France and Spain as well. Between 1061 and 1091, a bold Norman knight, Roger de Hauteville, with papal support and a small band of mercenaries, defeated the Muslims and Byzantines who controlled the island of Sicily. Roger then faced the problem of governing Sicily’s heterogeneous population of native Sicilians, Italians, Greeks, Jews, Arabs, and Normans. Roger distributed scattered lands to his followers so no vassal would have a centralized power base. He took an inquest of royal property and forbade his followers to engage in war with one another. To these Norman practices, Roger fused Arabic and Greek institutions, such as the bureau for record keeping and administration that had been established by the previous Muslim rulers.

In 1137, Roger’s son and heir, Count Roger II, took the city of Naples and much of the surrounding territory in southern Italy. The entire area came to be known as the kingdom of Sicily (or sometimes the Kingdom of the Two Sicilies).

Roger II’s grandson Frederick II (r. 1212–1250) was also the grandson of Frederick Barbarossa of Germany. He was crowned king of the Germans at Aachen and Holy Roman emperor, but he concentrated all his attention on the southern parts of the empire. Frederick had grown up in multicultural Sicily, knew six languages, wrote poetry, and supported scientists, scholars, and artists, whatever their religion or background. In 1224, he founded the University of Naples to train officials for his growing bureaucracy. He tried to administer justice fairly to all his subjects, including Jews and Muslims.

Sicily required constant attention, however, and Frederick’s absences on the Crusades and on campaigns in mainland Italy took their toll. Shortly after he died, the unsupervised bureaucracy fell to pieces. The pope, worried about being encircled by imperial power, called in a French prince to rule the kingdom of Sicily. Like Germany, Italy would remain divided until the nineteenth century.