Task: Question Generation
Input (English): The victorious great powers also gained an acknowledgement of their status through permanent seats at the League of Nations Council, where they acted as a type of executive body directing the Assembly of the League. However, the Council began with only four permanent members—the United Kingdom, France, Italy, and Japan—because the United States, meant to be the fifth permanent member, left because the US Senate voted on 19 March 1920 against the ratification of the Treaty of Versailles, thus preventing American participation in the League.
Output (English): When did US Senate vote against treaty of versailles ratification?