The feudal system’s origins can be traced back to late Roman imperial practices of land tenure. The biggest difference between feudal and late Roman practices is the feudal system contained a military obligation in return for holding land.
           The kings and leaders of the early Carolingian empire maintained bands of fighting men known as comitati, these bands of fighting men evolved into the later aristocracy of the Frankish kingdom. In the early eighth century Charles Martel began the practice of granting lands known as benefices to retainers in return for specified terms of military service. These lands were not hereditary at first there retention being conditional on fulfillment of service, but over time they became hereditary.
           This system began to break down after the death of Charlemagne and the ensuing civil wars fought between his descendants. Another factor that contributed to the chaos of the ninth and tenth centuries was the raids by the Vikings and Magyars which took advantage of the general disorder of the Franks. The situation did not improve until the accession of Hugh Capet to the throne of the West Franks in 987. The Capetian kings spent much time and effort enforcing their rights; this led to several wars with recalcitrant vassals. By the reign of Louis VI the Capetian’s had managed to enforce their feudal rights throughout the royal domain and in Normandy, Artois, Flanders, and Picardy.
The French kings also relied on the levy of all freemen known as the Arriere Ban especially in the Merovingian and Carolingian periods. As time went on and the need for heavy cavalry was more keenly felt the Ban was relied on less and less except in times of special need. Towards the end of the twelfth century there was more and more reliance on mercenaries who could be contracted for longer periods of the time than the traditional forty days of feudal service.
Feudalism evolved differently in other parts of Europe, one of the most complex situations being in the Norman states of southern Italy. The Normans initially entered southern Italy as bands of mercenaries seeking adventure and hired themselves out to the highest bidder. But as time went on they acquired fiefs and began to increase their holdings at the expense of the natives. By 1073 Robert Guiscard the Duke of Apulia controlled all of Sicily and southern Italy except for Benevento, Capua, and Naples. The Hallmark of feudalism in Norman Italy was the independence which was displayed by the Norman fief holders. Duke Robert spent much of his reign conducting innumerable sieges in an effort to bring rebellious vassals to heel.
In the early twelfth century Norman Italy became the Kingdom of Sicily. The kingdom was periodically plagued by rebellion which were put down and followed by confiscations of the lands of the most dangerous rebels. Little is known about the period of service required in the Kingdom of Sicily although forty days seems to be the standard time required. The kings of Sicily were not solely dependent on feudal service though, because the tax revenues of the kingdom allowed the king to hire mercenaries as needed.
           In England feudalism took on an entirely different form as a result of the Norman Conquest in 1066. Feudal obligations in England after the conquest were an amalgamation of Anglo-Saxon and Norman traditions. Cavalry did not become predominant until after the conquest the Anglo-Saxon’s had fought mostly on foot though the knightly class probably rode to battle. The Anglo-Saxon nobility maintained a retinue of military retainers called hauscarls that served as a small professional core for the larger fyrd, the semi-feudal arrays that were raised in wartime. After the Norman conquest King William I redistributed the lands of England to his followers and began the castellation of England. The Norman barons of England used their castles to dominate the country and impose their system of government on the English. The Normans also established some marcher holdings on the Welsh and Scottish frontiers; these were more independent lordships that sought to expand the kingdom.
           The crusader states of the Holy Land were considered the perfect feudal states as the kings of Jerusalem demanded and generally received their due of feudal service. In the aftermath of the First Crusade the Franks as they were known by the Muslims set up four states the counties of Tripoli and Edessa, the Duchy of Antioch, and the Kingdom of Jerusalem. The feudal system that developed in the Levant was a special case because the Kingdom of Jerusalem and its dependent fiefs were essentially under siege from their inception. The kingdom was lucky because it got a series of very capable men as King. Baldwin I and his successors were excellent strategists and they conducted there campaigns in such a manner as to make the most of their strengths while minimizing their weaknesses.
           The largest problem the crusader states faced was a lack of manpower. There were never very many colonists to the Holy Land so the crusader states were constantly short of men to defend them. They relied on pilgrims and a steady stream of crusaders to augment the Franks who lived in the Holy Land. They also took advantage of the relative anarchy that was occurring in the Muslim lands as the crusaders first arrived in the Levant. Eventually a leader, Salah-ad-Din or Saladin arose who managed to unify the Muslims on the borders of the Kingdom of Jerusalem. Beginning in 1183 Saladin conducted a brilliant campaign using all the resources at his disposal that led to the loss of most of the Kingdom of Jerusalem by 1187.