A further crucial figure entered the picture when Pope John XII appealed to Otto for protection against Berengar's attacks near Rome. It was a recognition of his role as protector of the papacy that Otto I was crowned emperor in February 962. Thus began the process of what was to become known as the renovatio imperii Romanorum--the 'renewal of the Roman Empire'. The relationship between pope and emperor was to be one of mutual dependency; the Ottonianum, the agreement drawn up between Otto I and John XII, had clauses inserted in it which demanded that a newly elected pope should take an oath to fulfil his obligations to the emperor, though these were, dangerously, not spelled out. The emperor in his turn would undertake to protect the interests of the Church and the see of St Peter. By the end of the tenth century, imperial activity in Italy was established in two, often interlinked, areas: the attempt to establish political hegemony over the old imperial territories in Italy and the protection of the position of the papacy.

The next hundred years saw frequent imperial interventions in northern Italy. Conrad II, in the first year of his reign, was promised the loyalty of the city of Milan by its bishop, Aribert, and went on to punish the citizens of Pavia for rioting and destroying the royal palace in the city, which, he reminded them, was a symbol of the state, not merely a private building. In 1026, he put down a revolt in Ravenna against the imperial officials and received the submission of Lucca as he moved southwards to Rome for his coronation. The 1030s saw a series of expeditions to impose obedience against the towns, which, as we shall later see, were, in the words of the contemporary historian Wipo, 'making a great turmoil . . . and covenanting together against their lords', moves which marked the beginning of the communal movement.

The assistance given to the papacy often consisted in disciplining the unruly nobles of the city of Rome itself. The position of pope, for so long a perquisite of the predominant urban faction, became one in which the western emperor took a personal interest and men of a much higher calibre began to hold the office. Many, such as the distinguished scholar

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