Eighty years ago today, on April 25, 1945 (March 14, 1945 in the lunar calendar), the United Nations Constitutional Convention opened. From August 21 to October 7, 1944, the three countries of the Soviet Union, the United Kingdom and the United States, the United Kingdom and the United States and the United Kingdom respectively held meetings in Dumbarton Oaks near Washington and passed the "Proposal on the Establishment of a Universal International Organization". The proposal named the international organization "United Nations" and stipulated the purposes and principles of the United Nations, the qualifications of member states, the composition and powers of the main organs. On April 25, 1945, the United Nations Constitutional Convention opened in San Francisco, USA. There were 282 delegates from 50 countries and more than 1,700 accompanying members. Chinese Communist Party leader Dong Biwu attended the meeting as one of the members of the Chinese delegation. Chinese representative Gu Weijun (left 1) discussed the draft UN Charter with representatives of the United States, the Soviet Union, Britain and France at the UN preparatory meeting in San Francisco. On June 25, the representatives of 50 countries unanimously adopted the UN Charter. The Charter stipulates that the purpose of the United Nations is to "maintain international peace and security" and to "promote the economic and social progress of the people of the world". Its basic principles are: sovereign equality, sincere fulfillment of international obligations, peaceful settlement of international disputes, prohibition of the threat or use of force, and non-interference in the internal affairs of other countries. The Charter also stipulates that the six main organs of the United Nations are the UN General Assembly, the Security Council, the Economic and Social Council, the Trusteeship Council and the Secretariat. An appraisal ceremony was held on June 26. This day was later designated as "Charter Day". October 24, when the UN Charter came into force, was designated as "UN Day". Dong Biwu, a Communist Party representative in the Chinese delegation, signed the UN Charter