The April Revolution, sometimes called the April 19 Revolution or April 19 Movement, was a popular uprising in April 1960, led by labor and student groups, which overthrew the First Republic of South Korea under Syngman Rhee. It led to the resignation of Rhee and the transition to the Second Republic of South Korea. The events were touched off by the discovery in Masan Harbor of the body of a student killed by a tear-gas shell in demonstrations against the elections of March 1960.
President Rhee had been in office since 1948, but faced increasing domestic discontent as his rule had delivered limited economic and social development, while being perceived as corrupt with Rhee amending the constitution to prolong his stay in power. The U.S. had reduced its economic aid from a high of $382,893,000 in 1957 to $222,204,000 in 1959. Rhee was shocked and threatened by this reduced American support and he began taking increasingly desperate measures to ensure his political survival. In December 1958 he forced through the National Assembly an amendment to the National Security Law giving the government broad new powers to curtail freedom of the press and prevent members of the opposition from voting.
For the 1960 presidential election, two main parties were running against Rhee. The small Progressive Party which received one million votes in the 1956 presidential election was represented by Cho Bong-am, while the Democratic Party was represented by Cho Pyong-ok. In July 1959 Rhee accused Cho Bong-am as being a Communist. He was imprisoned and swiftly executed. Cho Pyong-ok went to the United States for a stomach operation but died there of a heart attack. The death of these two competitors seemed too much of a coincidence to the Korean public and they assumed that the deaths were the result of corruption.
For the election of the vice president, which was done separately in Korea, Rhee was determined to see his protege Lee Ki-poong elected. Lee ran against Chang Myon of the Democratic Party, who was the former ambassador to the United States during the Korean War. On March 15 Lee, who was mostly bedridden, won the elections with an abnormally wide margin, winning 8,225,000 votes, while Myon received just 1,850,000 votes. It became clear to the people that the vote was fraudulent. According to the Korean Report, Democratic rallies were prohibited throughout the nation and hundreds of pre-marked ballots were stuffed into ballots on election day.