 In addition to various cabinet appointments, he served as Prime Minister of the Union of South Africa from 1919 until 1924 and from 1939 until 1948.From 1917 to 1919 he was one of five members of the British War Cabinet, helping to create the Royal Air Force.He played a leading part in the post-war settlements at the end of both world wars, making significant contributions towards the creation of the League of Nations and the United Nations.