History of Christianity. Lecture 19 of 30. From Charlemagne to the Holy Roman Empire. After the conquest of Italy by Justinian, the Popes found themselves subject to the whims of emperors in Constantinople. When the emperors were unable save Italy from the Lombards, the Popes looked for new protectors; they found the Franks. But this new relationship failed as well. The Papacy became a plaything in the hands of the Roman mob, local aristocrats, and foreign kings. An attempt to find a new protector - the Holy Roman Emperor - proved to be yet another disaster.