Seventy years ago this week, President Harry Truman signed into law the National Security Act of 1947. Here is what you should know about “the law that transformed America.”

1. The National Security Act of 1947 (hereafter “Act”) was a major reorganization of the foreign policy, intelligence, and military establishments of the U.S. government. The Act is “one of the most important pieces of legislation in modern American history,” says scholar Douglas Stuart. “No comparable omnibus legislation has been passed since that time, and it is safe to say that no comparable legislation could be enacted in the early 21st century.”

2. The Act created the National Security Council to “advise the President with respect to the integration of domestic, foreign, and military policies relating to the national security so as to enable the military services and the other departments and agencies of the Government to cooperate more effectively in matters involving the national security.” The Act also outlined who would be on the council: the President, the Secretary of State, the Secretary of Defense, the Secretary of the Army, the Secretary of the Navy; the Secretary of the Air Force, the chairman of the National Security Resources Board, and “such of the following named officers as the President may designate from time to time”—the Secretaries of the executive departments, the Chairman of the Munitions Board, and the chairman of the Research and Development Board.

3. Although the Act established the National Security Council, it makes no mention of the position of National Security Advisor. The only position outlined for the Council is “Executive Secretary.” It wasn’t until 1952 that Eisenhower appointed Robert Cutler to take the role of “Special Assistant to the President for National Security Affairs” to oversee the Council. Since then every president has appointed someone to serve as a NSA. (See also: What You Should Know About the National Security Advisor)

4. The Act created the Central Intelligence Agency and the role of Director of Central Intelligence (DCI). Part of the DCI’s role outlined in the Act is to “correlate and evaluate intelligence relating to the national security, and provide for the appropriate dissemination of such intelligence within the Government using where appropriate existing agencies and facilities.”

5. The Act replaced the Department of War—which had existed since 1789—with the Department of the Army. The Department of the Army was combined with the Department of the Navy and the newly created Department of the Air Force into the National Military Establishment (NME). The name of the NME was changed two years later to the Department of Defense (DoD).

6. The Act created the office of Secretary of Defense. As well as being in charge of the NME (now DoD), the Defense Secretary was designated as the principal assistant to the President in all matters relating to national security. The Secretary of War and Secretary of Navy were also removed from the presidential line of succession and replaced by the Secretary of Defense (currently sixth in line to the presidency).

7. After World War II, the fate of the U.S. Marine Corps (USMC) as a distinct branch was in jeopardy, as the Army had been pushing for a unified monolithic service (with the Army in control). The Act ensured the survival of the USMC by statutorily declaring its roles and declaring that the fleet marine forces shall be a part of our armed forces. As James D. Hittle wrote in 1947, this is “the only instance in which the National Security Act of 1947 makes any provision for the existence of an operating component of any of the armed services.”

8. The Act created the Department of the Air Force and transferred the United States Army Air Forces, the United States Army Air Corps, and the General Headquarters Air Force (Air Force Combat Command) over to the newly established U.S. Air Force.

9. The Act created the War Council (composed of the Secretary of Defense, Secretary of the Army, Secretary of the Navy, Secretary of the Air Force, Army Chief of Staff, Chief of Naval Operations, and the Air Force Chief of Staff) as well as the Joint Chiefs of Staff (Army Chief of Staff, Chief of Naval Operations, Air Force Chief of Staff, and the Chief of Staff to the Commander in Chief, if there be one).

10. The Act remained, as the CIA notes, the charter of the U.S. national security establishment until significantly altered with the passage of the National Security Intelligence Reform and Terrorism Prevention Act of December 2004, which created the Office of the Director of National Intelligence.

Joe Carter is an adjunct professor of journalism at Patrick Henry College, an editor for several organizations, and the author of the NIV Lifehacks Bible.

Photo Credit: President Truman in the Cabinet Room of the White House with the National Security Council on August 19, 1948. Photo by Abbie Rowe, via National Archives and Records Administration and Wikimedia Commons.