The UN System was built on developments from the 16th century onward. These are European traditions and experience in international law and organizations; the Concert of Europe; codified procedures for the prevention of war and the pacific settlement of conflicts in the Hague conferences; international public unions such as the Rhine Commission (1815) and the Danube Commission (1848), as well as that of the International Telegraphic Union (1865) and the Universal Postal Union (1874); and finally, the League of Nations. The first concrete step towards the establishment of the UN was taken when US President Roosevelt and British Prime Minister Churchill signed a joint declaration called the Atlantic Charter in August 1941. The Declaration by the United Nations was signed in January 1942 by twenty-six nations fighting against the Axis powers. Representatives from China, the Soviet Union, the United Kingdom and the United States gathered at Dumbarton Oaks in Washington D.C. to draft the charter and main principles of the new international organization. They produced Dumbarton Oaks Proposals on the basic structure of the organization in 1944. The United Nations Conference on the International Organization convened in San Francisco, and the UN Charter was unanimously accepted on June 26, 1945. It officially came into existence on October 24, 1945.