What Happens to Violence Once a Hierarchy Locks in?

David Geary says the formation of a hierarchy suppresses in-group violence once control is locked in.

Early polities follow a pattern, from states through larger empires. A lot of conflict comes at the beginning, when a hierarchy is established. A group of males, their kin, and their supporters take control of society and organize it. They develop systems for suppressing in-group competition and for suppressing people who want to displace them. There is a lot of violence at first, and then suppression of violence once the hierarchy is established. Eventually people get tired, revolts follow, or the rulers are displaced from outside.