According to Stubbs, a shift in English history took place under Edward I (reigned 1272–1307) when the feudal levy was replaced with royal payment in return for military service by the great magnates who willingly served the king. Thus, instead of vassals rendering military service when required by the lord, they paid a portion of their income into the lord's treasury. In turn the lord would supplement the owed military service with hired retainers, a sort of private army in full-time service to the lord.
