At the top of the feudal system were the monarchs. The position of monarchs of Europe became much weaker after the rule of Charlemagne; nevertheless, monarchs were still looked to as the highest authority. Gradually they lost their power to the lords and began to take on the position of an especially powerful lord, often ruling over several manors. However, monarchs often were the administrators of justice throughout their territories. Their vassals (servants) were obligated to provide military support if they were summoned.