Their main inspiration was the League of Nations; however, their goals were to rectify the League's imperfections[3] in order to create an organization that would be “the primary vehicle for maintaining peace and stability.”[4] Roosevelt's main role was to convince the different allies, especially Winston Churchill of the United Kingdom and Joseph Stalin of the Soviet Union, to join the new organization.[4] The negotiations mainly took place during the Dumbarton Oaks Conference and the Yalta Conference, where the three world leaders tried to reach a consensus concerning the United Nations' structure, purposes and principles.[5] “Roosevelt saw the United Nations as the crowning achievement of his political career.”[6] Roosevelt's envoy Wendell Willkie played a key role in promoting the idea of the United States joining the new organization, publishing One World (book) in April 1943.