The Paris Peace Conference convened on 18 January 1919. Although delegates from twenty-seven nations attended the conference, decisions were actually made by the ‘Council of Four’, the so-called ‘Big Four’ – Britain, France, Italy and the United States – and to a much lesser extent by Japan. Although the Peace Conference ended with the signing of the treaties with Germany (Treaty of Versailles, 28 June 1919) and Austria (Treaty of Saint-Germain-en-Laye, 10 September 1919), the four Powers, again only occasionally joined by Japan, continued to exert power as an Allied Supreme Council. After the German treaty was signed, the governing body of the Peace Conference became the Council of the Heads of Delegations of the Five Powers (Britain, France, Italy, the United States and Japan), called the Supreme Council. Japan was mainly excluded from, and had no real interest in, deliberations on the Middle East or the Balkans, leaving the other four to make decisions. America largely withdrew from Supreme Council considerations after the signing of the German and Austrian treaties, and as it had never been at war with the Ottoman Empire, power was in the hands of the remaining three. The Supreme Council deliberated on, and imposed, further treaties on other enemy nations and dealt with problems arising out of the original treaties. It was the Supreme Council that made the main Allied decisions on the Ottoman Empire.

Among the great European peace conferences, the Paris Congress was unique.