Severe disruption to the Jeju language community began after the end of Japanese rule in 1945. Following World War II, Korea was divided between an American-backed government in the South and a Soviet-backed government in the North. Popular opposition to the division of Korea and police brutality led to a rebellion against the American military government on April 3, 1948. The Syngman Rhee regime, which succeeded the American administration in August 1948, suppressed the rebellion with mass killings of civilians. As many as sixty thousand Jeju Islanders, or a full fifth of the pre-rebellion population, were killed. Forty thousand more fled to Japan. Out of the four hundred villages of the island, only 170 remained. The devastating impact of the massacres on the Jeju language community was exacerbated by the outbreak of the Korean War in 1950. While Jeju was never occupied by the North Korean army, nearly 150,000 Korean-speaking refugees from the mainland fleeing North Korean invasion arrived in Jeju in the first year of the war. These events shattered the Jeju language's former dominance on the island, and Standard Korean was beginning to displace Jeju in the public sphere by the 1950s.