Jan Smuts was one of the key figures behind the creation of the League of Nations; Woodrow Wilson was inspired by his ideas, including the mandates scheme. Smuts pleaded for a magnanimous peace, warning that the treaty of Versailles would lead to another war. Declaring "I return to South Africa a defeated man," Smuts encouraged John Maynard Keynes to write The Economic Consequences of the Peace. Smuts denounced the occupation of the Ruhr in 1923, became prime minister of South Africa, and made important contributions to the British cause in World War II.