A key figure in the establishment of the United Nations was Dag Hammarskjöld, who served as the organization’s second Secretary-General from 1953 until his death in 1961. Hammarskjöld focused on fostering international cooperation and peacekeeping efforts during the Cold War era. He was instrumental in developing the UN's peacekeeping forces and advocated for collective action in conflict resolution. His dedication to diplomacy and humanitarian efforts continues to influence international relations today, and he is remembered for his commitment to the ideals of the UN and global peace.