In World War I France and the United Kingdom invade Cameroon (1914). After the war, in 1919, Cameroon is divided into French Cameroons and British Cameroons. In 1922 French Cameroons becomes a League of Nations mandate, converted into a United Nations Trust Territory in 1946. France grants Cameroons internal self-government in 1957. André-Marie Mbida becomes the first prime minister. He is succeeded by Amadou Ahidjo, leader of the Union Camerounaise (Cameroon Union, UC), in 1958.
When Cameroon becomes independent as the Republic of Cameroon in 1960, Ahidjo is the first president. In 1961 Cameroon unites with the southern part of British Cameroons as the Federal Republic of Cameroon. The UC merges in 1966 with the Kamerun National Democratic Party (KNDP) and other parties into the Union Nationale Camerounaise/Cameroon National Union (UNC). Ahidjo outlaws all other political parties that year. At that moment Cameroon becomes a de facto one-party state, which is confirmed in 1972 when democracy is formally abolished. At the same time the country is renamed United Republic of Cameroon in 1972. Ahidjo unexpectedly in 1982 and is succeeded by Paul Biya. The country is again renamed Republic of Cameroon in 1984 and the UNC is renamed Rassemblement démocratique du Peuple Camerounais/Cameroon People's Democratic Movement (RDPC) in 1985
In 1990 the formation of political parties is permitted and in 1992 Cameroon becomes a multiparty democracy. In the first elections the RDPC becomes the largest party without an overall majority and Biya wins in 1992 narrowly the presidential elections. Although formally a democracy, the old regime of the RDPC continues to rule in an authoritarian way, and the opposition boycotted the 1997 and 2002 elections.