In the eleventh century a small group of clerical reformers based in Rome launched a fight for the liberty of the Church. The consequences ultimately included a politically powerful papacy and stronger kingdoms with their own more secular laws and bureaucracies. One way to understand what happened is to examine the life of Peter Damian, the most prolific Latin writer of the mid eleventh century and a pioneer in the reform movement. He has never before received a comprehensive critical historical biography.

Peter was an orphan boy from Ravenna who became a successful professor of rhetoric. Then he abandoned that career to join a community of penitent hermits living in the high Apennines at Fonte Avellana. He did not actually manage to leave the world behind because he was chosen as prior of his hermit community and had to employ his rhetorical and legal skills to protect it from predatory local lords and “bad bishops and abbots.” He cultivated contacts with the emperor and the pope. In 1057 he was named bishop of Ostia, the leader of the cardinal bishops. As a high official in the Roman Church, aided by his prolific writings, he promoted a reforming agenda. He proved to be a formidable papal legate. At the end of his career, he retired to Fonte Avellana where he remained active until he died on a final legatine mission, probably in 1073.

Peter advanced the movement known today as the “Gregorian Reform” not only by strengthening papal power and canon law but also by helping to develop a powerful curial bureaucracy with new means of communication that gave the Roman curia more control over local churches. His successes, failures, and misadventures illuminate a major turning point in Western civilization.