The need for establishing an international body for the maintenance of world peace was felt from the very start of the World War During the course of the Second World War the big powers initially met in conferences and drew a road map to a world body.
In fact, many declarations and charters were signed and issued by the leaded of the Allied Powers. In this respect mention may be made of the London Declaration, Atlantic Charter, Moscow Declaration, etc. It was in the Moscow Declaration that for the first time the necessity for the formation of the UNO was recognized clearly.
The Foreign Ministers of USA, France, Great Britain and USSR announced a common program for the early establishment of an international organization. In the Atlantic Charter the US President Roosevelt and the British Prime Minister Churchill declared that some arrangements shall have to be made in order to allow every country to live in peace and to remain free.
The Yalta Conference was a positive step forward towards the formation of the UNO. It was decided in the Conference that an international body will be established on the basis of the proposals accepted in the earlier conferences.
It was at the San Francisco Conference that the final drafting of the UN Charter of the proposed organization was completed. On 26 June 1945 representatives of 50 nations participating in the conference signed and accepted the Charter of the United Nations. And on 24 October 1945 the UNO was formally established. When the UNO started functioning its total number of members was 51.