Koryŏ military officers revolted in 1170. The subsequent twenty-six years were disastrous: the new military leaders, unable to create a stable political environment, resorted to coups and countercoups. Assassination became common. This uncertainty at the top fomented discontent below. Buddhist monks, disaffected civilian officials, peasants, and slaves took up arms. Newly promoted generals tried to take charge, but their efforts consistently were frustrated by widespread corruption and greed.
Ch'oe Ch'unghŏn, another general, came to power through a coup d'etat in 1196. To establish his authority, and check the drift toward anarchy that had characterized Myŏngjong's reign (1170-1197), he forced the king to abdicate, purged many leading military officials, and immediately launched a far-reaching reform program. Ch'unghŏn ruled Koryŏ primarily through his position as the dominant military power, but after purging potential military rivals, he looked to civilians, and civilian institutions, to assist him in restoring order to Koryŏ. He also developed his own institutions, responsible to him alone, to streamline the administration. Ch'oe increasingly worked through this new system to manipulate the dynasty. By the time of his death in 1219, much of the discontent, rebellion, and corruption that had destabilized the dynasty had disappeared.