He led Boer forces during the Second Boer War, but afterwards supported Louis Botha’s policy of Anglo-Boer cooperation and was one of the founders of the Union of South Africa. During World War I he led Allied troops against the Germans in East Africa (1916); he later attended the peace conference at Versailles in 1919 and helped to found the League of Nations. He then succeeded Botha as Prime Minister. After World War II Smuts played a leading role in the formation of the United Nations and drafted the preamble to the UN charter.