Major events leading to the establishment of the United Nations include the devastation of World War II and the recognition of the need for a global organization to maintain peace and prevent future conflicts. The formation was officially proposed during the Yalta Conference in 1945, where leaders from the Allied powers discussed post-war order. The signing of the UN Charter in San Francisco marked the formal creation of the organization on October 24, 1945. Key principles included promoting international cooperation, human rights, and social progress. The UN aimed to provide a platform for dialogue and conflict resolution, ultimately striving to foster global peace and security.