Subinfeudation was the quintessential mechanism of the feudal hierarchy in medieval England, allowing the Great Barons (tenants-in-chief) to alienate parts of their holdings to lesser nobles or knights. This process created a chain of tenure, where each lord acted as a mesne lord, standing between the King and the ultimate tenant in possession of the land (the tenant paravail). The relationship was defined by the 'feodum' or fief, and secured through the ceremony of homage, ensuring that military obligations—such as knight-service—could be subdivided and fulfilled across a vast estate.
This system led to increasingly complex legal structures as strings of intermediary lords grew, often complicating the collection of feudal incidents like wardship and escheat. To prevent the dilution of the Crown's rights and the loss of service control, the practice was effectively curtailed by the Statute of Quia Emptores in 1290. This landmark legislation mandated that any subsequent transfer of land must be by substitution rather than subinfeudation, fundamentally altering the evolution of English land law and contributing to the decline of the pure feudal state.