Jeju uprising to Jeju from Busan and deploying police companies, each 1,700 strong, from the southern provinces of the mainland. The guerrillas retreated to their bases in the forests and caves around Hallasan, an extinct volcano and the highest mountain in South Korea. On April 29, the Korean, non-military, governor of Jeju province abandoned his post, defected, and joined the guerrillas. This caused many police officers, disillusioned by the atrocities they were ordered to commit against their own, to do the same. In response, U.S. military provincial governor William F. Dean ordered a purge of SKLP sympathizers from the ranks of the
Hallasan in Jeju Island. There is a memorial site outside the temple to commemorate the victims of the Jeju uprising that took place between 1948 and 1950. It is one of the most visited places on the island. There are five hiking trails on Hallasan. The Donnaeko trail was reopened to the public on December 4, 2009, after a fifteen-year hiatus. Only the Gwaneumsa and Seongpanak trails lead to the summit. The Donnaeko, Eorimok and Yeongsil courses only go as far as Witse Oreum (윗세오름), as the rest of the trail leading to the peak has been closed off since 1994