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 Thus, the distribution of mammals in Jeju Island is very poor in species and numbers because Jeju island is isolated from the Korean peninsula long ago. Their population has been reduced due to the decrease in food because of the use of rodenticides and pesticides in recent years and indiscreet fishing. Weasels, badgers, and gazelles are inhabited in Hallasan. The number of weasels and badgers are significantly reducing. Boar and Formosan deer is already extinct. Roe deer, the largest mammal in Hallasan, was once in danger of extinction. But now its population increased due to protection policies and a lot