November 15, 1920- The League of Nations was founded immediately after the First World War. It was created because a number of people in France, South Africa, United Kingdom, and the United States believed that a world organization of nations could keep the peace and prevent repetition of the First World War in Europe. The League aimed to preserve peace through collective action and disarmament and thus promoting international cooperation in economic and social affairs. As the Second World War unfolded it became clear that the League had failed at its chief aim at keeping the peace.

June 12, 1941- The Inter-Allied Declaration which was signed in London and was the first step towards the establishment of the United Nations.

August 14, 1941- Signing of the Atlantic Charter.
In a meeting on the ship HMS Prince of Wales, "somewhere at sea" the signing of the Atlantic Charter took place. President Franklin Roosevelt of the United States and Prime Minister Winston Churchill of the United Kingdom proposed a set of principles for international collaboration in maintaining peace and security.

January 1, 1942- UN Declaration.
Representatives of the 26 Allied Nations fighting against the Axis Powers (Japan, Germany, and Italy) met in Washington D.C. and pledged their support for the Atlantic Charter by signing the "Declaration of United Nations". This document contains the first official use of the term "United Nations" which was suggested by President Roosevelt.

September 21-October 7, 1944-Dumbarton Oaks Conference.
At this conference at Dumbarton Oaks, Washington D.C. the first blueprint of the United Nations was drafted. The United States, the United Kingdom, the Soviet Union, and China agreed on the aims, structure, and functioning of a world organization.

February 11, 1945- Yalta Conference.
The meetings of the Big Three (United States, United Kingdom, and the Soviet Union) in Yalta, USSR which promoted their resolve to establish "a general international organization to maintain peace and security".

April 25,1945- San Francisco Conference.
The delegations of 50 nations met in San Francisco met to draw up the Charter with 111 articles. Successfully, the Charter was adopted unanimously on June 25, 1945.

October 24, 1945- The Birth of the United Nations.
It was created as its Charter was ratified by the five permanent members of the Security Council, which is the United States, United Kingdom, France, China, and the Soviet Union.