Liberia was the first African republic to proclaim its independence and is Africa's first and oldest modern republic. It was among the few countries to maintain its sovereignty during the Scramble for Africa. During World War II, Liberia supported the United States war effort against Germany, and in turn received considerable American investment in infrastructure, which aided the country's wealth and development. President William Tubman encouraged economic and political changes that heightened the country's prosperity and international profile; Liberia was a founding member of the League of Nations, United Nations, and the Organisation of African Unity.