Westeros had no system of dukes, marquesses, earls, viscounts, and barons; it had only higher and lower vassals. This was why the protagonist could promise land as private property: he already had land he could grant to several lesser vassals.
All he had to do was declare that the land would be inherited by that person's family in perpetuity in exchange for an oath of fealty. That person would immediately become a minor lord, but would also lose the right to manage or reclaim the land.
Vassals needed to provide military forces for their lords.
According to George R. R. Martin, "Lords have vassals, vassals have vassals, and sometimes a vassal's vassal has vassals too, all the way down to the fifth level of vassal." Poor relations between a lord and a vassal could lead to the vassal withholding all military support.
However, even vassals who stood by their lords might withdraw their support if a cause ended in failure.
Vassals could act in their own interests, sometimes to the detriment of their lords. A vassal's dishonorable behavior could bring shame and security problems upon his lord.
Vassals could test a new lord to judge his abilities. (They had the autonomy to make decisions about marriage, alliances, diplomacy, and declarations of war, and their lord was not allowed to interfere.)
Some lords set their vassals against one another so they could keep discovering their weaknesses.
As part of a peace agreement, a lord could demand that his vassals send their relatives to serve as hostages.
Lord: Under the feudal system of the Seven Kingdoms, Lord was an inheritable noble title. A lord's status was reflected in the ties between lords, who were connected through their ownership of numerous strongholds. All lords had vassals, and vassals could have knights; the feudal