On 1st January 1942, President Franklin D. Roosevelt, supported by the representatives of 26 countries, published the Declaration by United Nations, a document that pledged their governments to continue fighting together against Nazi Germany and Japan during the Second World War.
This declaration was followed by a conference of Foreign Ministers in Moscow, in October, 1943 where discussions took place concerning a replacement for the discredited League of Nations.
Further talks took place at San Francisco between 15th April and 26th June, 1945. Delegates from fifty nations that had been at war with Germany, decided on the design and structure of this new organization. The conference drafted the United Nations Charter and it was signed on 26th June and ratified at the first session of the General Assembly of the United Nations in London on 24th October 1945.
The main differences between the League of Nations and the United Nations were the stronger executive powers assumed by the Security Council and the requirement that member states should make available armed forces to serve as peace-keepers or to repel an aggressor.
The Security Council had five permanent members, United States, the Soviet Union, China, France and Britain. Six other countries served two-year periods on the Council (this was increased to ten in 1965). Controversially, permanent members were given the power to veto decisions made by the Security Council. The other nations vigorously opposed the idea of the veto but it became clear that without such a favoured position the five major nations would not join the United Nations. The United States Senate ratified the United Nations treaty by a vote of 89 to 2 on 28th July, 1945.