Originally Posted by Chookie
Empires are only feudalism writ large. An Emperor or Empress is the absolute top of an economic and socio-political pyramid but so is each and every feudal superior. The only discernible difference is in the amount of forces available to that superior.
My take on feudalism - over-rated and not all that good for society.
A provincial governor's son is not guarenteed to become a governor, and the governor himself does not own the province, he 'leases' it under order of the emperor. The men beneath the governor are, theoretically at least, loyal to the emperor and not the governor directly. Empires normally have some kind of standing army as well, that is directly loyal to the emperor, which provides the bulk of an empire's military power.
Under a feudal system the lords are directly loyal to the king, and the nobles are directly loyal (have oaths to) the lords, and the freemen are directly loyal to their respective nobles.
This means that if a provincial governor wants to rebel, he must ensure that the troops stationed in his province want the same thing. He is in command of the troops on the ground, but can be superceded or recalled by the emperor at any time.
Feudalism does not work this way. If a feudal lord wants to rebel, he has his entire holdings to use. The king does not have direct control over any of his holdings, nor any oaths made to the lord. Thus the lord has an army (albeit not likely to be a large one) that is loyal to him alone.
The bulk of military power is not directly under the control of the king - during times of war, he summons his lords and nobles and they bring their own men to fight under his banner (a good example of this is Henry V's campaigns in France - each lord is obliged to provide X men).
This is all simplified for the sake of argument, and I know there will be many exceptions to the rule, but this is the gist of how a feudal system works compared to an empire.