 After the war, as outlined in the Treaty of Versailles, Germany was forced to cede "control" of the Western section of the former German East Africa to Belgium.On 20 October 1924, Ruanda-Urundi (1924–1945), which consisted of modern-day Rwanda and Burundi, became a Belgian League of Nations mandate territory, with Usumbura as its capital.During World War II the Belgian Congo served as a crucial source of income for the Belgian government in exile in London after the occupation by the Nazis.