European and U.S. reformers exposed the conditions in the Congo Free State to the public through the Congo Reform Association. Also active in exposing the activities of the Congo Free State was the author Arthur Conan Doyle, whose book The Crime of the Congo was widely read in the early 1900s. By 1908, public pressure and diplomatic manoeuvres led to the end of Leopold II's rule and to the annexation of the Congo as a colony of Belgium, known as the Belgian Congo.