Chadae of Goguryeo

Chadae, younger brother of the aged Taejo, usurped the throne by force. He killed several of Taejo's sons and supporters, establishing a reign of terror that marked a sharp break from the stability of his predecessor.

Chadae initiated a series of purges against the nobility and royal family, executing or exiling anyone he perceived as a threat. This created an atmosphere of fear, weakened the central government, and alienated the powerful clans.