After the assassination of Park Chung-hee, Prime Minister Choi Kyu-hah took the president's role only to be usurped 6 days later by Major General Chun Doo-hwan's 1979 Coup d'état of December Twelfth. In May of the following year, a vocal civil society composed primarily of university students and labour unions led strong protests against authoritarian rule all over the country. Chun Doo-hwan declared martial law on May 17, 1980, and protests escalated. Political opponents Kim Dae-jung and Kim Jong-pil were arrested, and Kim Young-sam was confined to house arrest.