Various considerations suggested to Frankish rulers and nobles the expediency of endowing these followers with land, and of granting land to no tenant unless he would take the vassal's oath. Usually land was the only form of pay which the lord could give; and it always served as a material guarantee of faithful service, since it could be resumed whenever the vassal made default. In days when law and morality availed little as the sanctions of contracts, the landlord naturally desired to bind his tenant to him by a personal obligation; and there were obvious advantages in providing that every tenant should be liable to aid his lord with arms. The estates granted to vassals were known as benefices (beneficia); they foreshadowed the lay-fief of later times. But there are some distinctions to be drawn. The benefice was not de jure heritable; it escheated on the death of either lord or tenant. The service was not measured with the same precision as in later times. The military duties of the beneficed vassal were not different in kind or degree from those of the ordinary freemen. Finally, the idea had not yet arisen that vassals were superior in status to the rest of the community. The importance of the vassal depended entirely on his wealth and his rank in the King's employ. Only in the old age of the Carolingian Empire, when the class of free landowners, acknowledging no lord, had been almost ground out of existence by official oppression and the intolerable burden of military service, was the burden of national defence thrown entirely upon vassals. Then, as the sole military class in the community, they acquired the consideration which, in early stages of social development, is the monopoly of those who are trained to arms.
(2) It was natural that the tie of vassalage should be imposed on every important official; and natural also to regard his office as a benefice, tenable for life or during good behaviour. At an early date we find cases of conquered princes - a Duke of Aquitaine, a Duke of Bavaria, a King of Denmark - who take the vassal's oath and agree to hold their former dominions as a beneficium. So again a member of the royal house does homage and promises service in return for his appanage. More common, and more important for the future, is the practice of treating counts as vassals. All over the Frankish Empire the county was the normal unit of local administration. The count led the military levies, collected the royal dues, enforced the laws, maintained the peace, and was a judge with powers of life and death. The Carolingians controlled their counts by means of itinerant inspectors (missi dominici); but with the disruption of their Empire this check was destroyed, while the power of the count survived. By that time the office had often become hereditary, on the analogy of the beneficium, and the count appropriated to his own use the profits of his office. In such cases his county became a small principality, classed by lawyers as a fief, but often ruled without any reference to the interests of the royal overlord. The fiefs of Anjou, Champagne and Flanders began in this way as hereditary countships. Sometimes, again, we find that a great vassal obtains, by grant of usurpation, the prerogatives of a count over his own lands; examples are the prince-bishops of Trier (898 A.D.), Hamburg (937), and Metz (945).
The first effect of this striking change in the nature of landed property and of public office was to substitute for the centralised state of the Carolingians a lax federal system, in which each unit was a group of men attached to the person of a hereditary superior. This nascent feudalism was often brutal, always summary and short-sighted, in its methods of government. The feudal group was engaged in a perpetual struggle for existence with neighbouring groups. Feudal policy was aggressive; for every lord had his war-band, whom he could only hold together by providing them with adventure and rich plunder; nor could any lord regard himself as safe while a neighbour of equal resources remained unconquered. Furthermore, as though the disintegration of society had not gone far enough, every great fief was in constant danger of civil war and partition. As the lord had treated the King, so he in turn was treated by his vassals. He endowed them with lands, he allowed them to found families, he gave them positions of authority; and then they defied him. In the eleventh century the great fief bristled with castles held by chief vassals of the lord; in the small county of Maine alone we hear of thirty-five such strongholds; generally speaking they were centres of rebellion and indiscriminate rapine. Such feudalism was not a system of government; it was a symptom of anarchy.