The Holy Roman Empire, created when the pope crowned Charlemagne in 800, would endure for slightly more than a thousand years. Although from time to time a particuarly able emperor would assert Imperial unity and authority (Henry the Fowler, Otto the Great, Conrad II, Frederick Barbarossa, and Frederick II ), for most of its history the empire was, in Voltaire's phrase, "Neither Holy, nor Roman, nor an Empire." France broke off early (by the late 9th century), and other regions gradually went their own way as well. The emperors were constantly feuding with the popes about their respective spheres of authority (supposedly the emperors were the supereme temporal and the popes the supreme spiritual heads of Christendom, but they each tended to interfere in the other's area), and the result was an unpleasant series of wars. Nevertheless, since the emperors tended to be among the most powerful landowners in Germany, they were often a force to be reckoned with.