The first Republic of Korea existed from August 1948 to April 1960 and was the government of South Korea. It was established on August 15th, 1948, after the transfer of power from the United States Army Military Government which had been governing South Korea since the end of Japanese rule in 1945. This was the first independent republican government in Korea, with Syngman Rhee being elected as the first president of South Korea in May 1948 and the National Assembly in Seoul adopting the first constitution in July of the same year, which established a presidential system of government. The first republic claimed to have authority over all of Korea but only controlled the area south of the 38th parallel until the end of the Korean War in 1953, after which the border was changed. The first republic was marked by the authoritarian rule and corruption of Rhee, limited economic development, strong anti-communism, and by the late 1950s, increasing political instability and public opposition to Rhee. The April Revolution in 1960 led to Rhee's resignation and the beginning of the second Republic of Korea.