After months of planning, the UN Conference on International Organization opened in San Francisco in April 1945 attended by 50 governments and a number of non-governmental organisations involved in drafting the United Nations Charter. The heads of the delegations of the four sponsoring countries (the U.S., the U.K., the Soviet Union, and China) invited the other nations to take part and took turns as chairman of the plenary meetings beginning with Anthony Eden of Britain. At the later meetings, Lord Halifax deputized for Eden. The UN officially came into existence on 24 October 1945 upon ratification of the Charter by the five permanent members of the Security Council—the U.S., the U.K., France, the Soviet Union and the Republic of China—and by a majority of the other 46 signatories. Gladwyn Jebb served as Acting Secretary-General from 24 October 1945 to 2 February 1946 until the election of the first Secretary-General.