(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).