In medieval and early modern Europe, a tenant-in-chief (or vassal-in-chief) was a person who held his lands under various forms of feudal land tenure directly from the lord paramount to whom he did homage, as opposed to holding them from another nobleman or senior member of the clergy. The tenure was one that denoted great honour, but also carried heavy responsibilities. The tenants-in-chief were originally responsible for providing knights and soldiers for the king's feudal army.
Terminology
The Latin term was tenens in capite.
Other names for tenant-in-chief were "captal" or baron, although the latter term evolved in meaning. For example, the term "baron" was used in the Cartae Baronum of 1166, a return of all tenants-in-chief in England. At that time the term was understood to mean the "king's barons", or "king's men", because baron could still have a broader meaning. Originally, for example in Domesday Book (1086), there was a small number of powerful English tenants-in-chief under the Norman king who were all magnates directly associated with the king.
Later, as laid-out by I. J. Sanders, the old tenancies-in-chief of England from the time of the Norman king, King Henry I of England, came to have a legally distinct form of feudal land holding, the so-called tenure per baroniam. The term "baron" thus came to be used mainly for these "feudal barons", which comprised a group that over-lapped with the tenancies-in-chief, but was not identical.
History
In most countries allodial property could be held by laypeople or the Christian Church. However, in the Kingdom of England after the Norman Conquest, the king became in law the sole lord paramount and only holder of land by allodial title. Thus all the lands in England became the property of the Crown. A tenure by frankalmoin, which in other countries was regarded as a form of privileged allodial holding, was in England regarded as a feudal tenement. Every land-holding was deemed by feudal custom to be no more than an estate in land, whether directly or indirectly held of the king. Absolute title in land could only be held by the king himself: the most anyone else could hold was a right over land, not a title in land per se.
When an heir came of age, he or she passed out of wardship but could not enter upon their inheritance until, like all heirs of full age on inheritance, they had sued out their livery. In either case, the process was complicated.