The Chairman of the Joint Chiefs of Staff is the nation's highest-ranking military officer. He presides over the Joint Chiefs of Staff and provides military advice to the civilian leadership. Soon after the Joint Chiefs of Staff came into existence during World War II, Admiral William D. Leahy became its presiding officer. This arrangement continued after the war, with General of the Army Dwight D. Eisenhower serving briefly after Leahy's departure in early 1949. When the National Security Act of 1947 gave legal sanction to the Joint Chiefs of Staff, it did not authorize a chairman. However, service disagreements over roles, missions, and the allocation of funds to meet the growing threat from the Soviet Union led Congress to create the position of Chairman of the Joint Chiefs of Staff in 1949. General Omar N. Bradley, USA, became the first Chairman on August 16 of that year. Although law, executive action, and practice extended the Chairman's role during three subsequent decades, is authority remained restricted and he served essentially as the fir among equals on the JCS. In 1986, however, believing that the JCS system required fundamental reform, Congress enacted the Goldwater-Nichols Department of Defense Reorganization Act, which greatly expanded the Chairman's authority and reponsibilities.