 In addition to various Cabinet appointments, he served as Prime Minister of the Union of South Africa from 1919 to 1924 and from 1939 to 1948.He played a leading part in the post war settlements at the end of both world wars, making significant contributions towards the creation of both the League of Nations and the United Nations.This article is about Jan Smuts' role in the Second Boer War, from the outbreak of war in 1899 until the Treaty of Vereeniging in 1902.