Liberia remained neutral during World War I until August 4, 1917, when it declared war on Germany. In 1919 Liberia attended the Versailles Peace Conference. Liberia was one of the founding members of the League of Nations when it was founded in January 1920.
Middle 20th Century:
In 1929 allegations of modern slavery in Liberia led the League of Nations to establish the Christy commission. Findings included government involvement in widespread “Forced or compulsory labour”. Minority ethnic groups especially were exploited in a system that enriched well-connected elites. As a result of the report, President Charles D. B. King and Vice President Allen N. Yancy resigned.
In the mid-20th century Liberia gradually began to modernize with American assistance. During World War II the United States made major infrastructure improvements to support its military efforts in Africa and Europe against Germany. It built the Freeport of Monrovia and Roberts International Airport under the Lend-Lease program before its entry into the Second World War.
After the war President William Tubman encouraged foreign investment in the country. Liberia had the second-highest rate of economic growth in the world during the 1950s.
Liberia also began to take a more active role in international affairs. It was a founding member of the United Nations in 1945 and became a vocal critic of the South African apartheid regime. Liberia also served as a proponent both of African independence from European colonial powers and of Pan-Africanism, and helped to fund the Organisation of African Unity.
Late 20th-Century Political Instability:
On April 12, 1980, a military coup led by Master Sergeant Samuel Doe of the Krahn ethnic group overthrew and killed President William R. Tolbert, Jr. Doe and the other plotters later executed a majority of Tolbert’s cabinet and other Americo-Liberian government officials and True Whig Party members. The coup leaders formed the People’s Redemption Council (PRC) to govern the country. A strategic Cold War ally of the West, Doe received significant financial backing from the United States while critics condemned the PRC for corruption and political repression.
After Liberia adopted a new constitution in 1985, Doe was elected president in subsequent elections that were internationally condemned as fraudulent. On November 12, 1985, a failed counter-coup was launched by Thomas Quiwonkpa, whose soldiers briefly occupied the national radio station. Government repression intensified in response, as Doe’s troops retaliated by executing members of the Gio and Mano ethnic groups in Nimba County.
The National Patriotic Front of Liberia (NPFL), a rebel group led by Charles Taylor, launched an insurrection in December 1989 against Doe’s government with the backing of neighboring countries such as Burkina Faso and Ivory Coast. This triggered the First Liberian Civil War. By September 1990, Doe’s forces controlled only a small area just outside the capital, and Doe was captured and executed in that month by rebel forces.