I have spoken of those volonteers who, among the Germans, followed the princes in their enterprises. The same practice continued after the conquest. Tacitus designates them by the name of companions,  the Salic law by the name of men who owe fealty to the king,  the formularies of Marculfus  by that of antrustions of the king,  our first historians by that of leudes, of fidèles,  and those who came later by the name of vassals and lords. 
We find in the Salic and Ripuarian laws an infinite number of provisions for the Franks, and only a few for the antrustions. The provisions for these antrustions are different from those made for the other Franks : all kinds of rules apply to the Franks’ possessions, and nothing is said of those of the antrustions, which comes from the fact that the antrustions’ property is regulated rather by political law than by civil law, and that it was the lot of an army and not the patrimony of a family.
The property reserved for the leudes was called fiscal property, benefices, honors, and fiefs in different authors and in different times. 
There is no doubting that fiefs at first were revocable.  We see in Gregory of Tours  that everything Sunegisilus and Gallomanus got from the treasury was taken away, and they are left only with what they held as property. Gontram, raising his nephew Childebert to the throne, had a secret conference with him, and indicated to him those  to whom he should give fiefs, and those from whom he should take them. In a formula of Marculfus,  the king gives in exchange not only benefices which his treasury held, but also those which another had held. The law of the Lombards opposes  benefits to property. The historians, the formulas, the codes of the different barbarian peoples, and all the subsisting documents are unanimous. Finally, those who wrote the book of fiefs tell us that at first the lords could take them away at will,  that subsequently they guaranteed them for a year,  and after that gave them for life.