Treaty of Paris
The Treaty of Paris (formally the Treaty establishing the European Coal and Steel Community) was signed on 18 April 1951 between France, West Germany, Italy and the three Benelux countries (Belgium, Luxembourg, and the Netherlands), establishing the European Coal and Steel Community (ECSC), which subsequently became part of the European Union. The treaty came into force on 23 July 1952 and expired on 23 July 2002, exactly fifty years after it came into effect.
The treaty was seen as producing diplomatic and economic stability in western Europe after the Second World War. Some of the main enemies during the war were now sharing production of coal and steel, the key-resources which previously had been central to the war effort.
— Wikipedia
Signature page of the Treaty of Paris.