After the end of the Second World War, i.e. after the end of hostilities, it was signed in
(REIMS) in 08/05/1945 to hand over Germany, then, on 05/06/1945 a statement includes
the defeat of Germany and the recognition of the governments of the United States, England,
and France was released giving the right to the supreme authority to act. After this, the
The United States sent Judge (Jackson), to negotiate with representatives of other countries on
the idea of ​​achieving the trial of war criminals.
After his return from England, France, and occupied Germany, and gathered facts and
information and listened to several prisoners and witnesses, he returned to his country
and raise a serious report to the President (Truman) on 06/06/1945 in which he explained the
crimes committed by the Nazi leaders and organizations in general, and his conception of
the International Tribunal which will try them and restrict the jurisdiction of this
International Criminal Court to prosecute big war criminals whose crimes do not have a
specific geographical placement, its composition, and the procedures of trial before it.
At the Potsdam Conference (Russia) in the period from 17/07/1945 up to 02/08 for the
year between (Truman, Stalin, and Churchill) (Attlee replaced Churchill starting from
28/07 because of the fall of the latter in the elections), in which Chapter IV of the
agreement reached by the presidents in this conference was allocated for the trial of war
criminals and saying that the three governments had taken note of the controversy about
the views that have occurred in recent weeks in London between Britain, America and
France representatives to reach agreement on the ways of trial of the major war criminals
for their crimes that have no particular geographical place. These three governments
reaffirm their intention to apply real and quick justice to those criminals.

The events of World War II were like a rock that crashed (the League of Nations) which
revealed its serious weaknesses, and its inability to cope with the serious violations of the
international system, and the lack of success in international peace and security keeping.
The Allied Powers realized this fact during the war, it came in the Atlantic Charter signed
in 14/8/1941 between (Roosevelt and Churchill) that presidents hope, after the elimination
of Nazism, that all the nations will be able to get rid of fear and want, and be able to
live with international peace and security, as it will ensure the organization of the new
international plan after the end of hostilities.
On the first of January 1942, representatives of twenty-six countries met in Washington and
issued a statement called (United Nations statement) stating that they will make efforts in
order to reach a new international organization to ensure the restoration of international
peace and security in the world, and 30/10/1943, the famous Moscow statement was
issued and in one of its paragraphs came the expression of the desire of the four countries
representatives to establish a public international body to replace the League of Nations.
The Conference of (Yalta) confirmed the resolve to invite nations to hold the San
Francisco Conference and a preliminary conference was held for this purpose in
(Dumbarton Oaks) in Washington on 17/10/1944 between the representatives of Britain
and the United States, Russia, and China, and it ended with the development of a
preliminary project for the establishment of a new international body, then States were
invited to the conference in San Francisco held from 25/04 to 26/06/1945 to look at the
project. Representatives of fifty countries attended this conference.

On 26/06/1945, the fifty states approved the Charter (of the United Nations) after the
introduction of some amendments to the draft of (Dumbarton Oaks), and entered into force
on 24/10/1945.
Sources:
It was used as a set of international laws and research.