The League of Nations failed to prevent a new world war. The World War II (1939-45), more terrible, more destructive than the first one, was fought on much larger areas of Europe, Asia and Africa than the earlier one. The Second World War gave a new impetus and urge to set up a new world organisation to put an end to war and to preserve peace in the future.
With this end in view, 43 Allied nations, fighting against Hitlerite Germany, Fascist Italy and Japan declared themselves as United Nations on January 1, 1942. At the end of the World War II, a world conference of 50 nations met at San Francisco, in U.S.A., from April to June, 1945. On the 26th June, 1945, a constitution of the United Nations was prepared, called the Charter.
It was finally signed and ratified by the majority of the participating nations on 24th October 1945, when the United Nations Organisation (U.N.O.) came into being.