NATO History: A 75-Year Alliance

Seventy-five years ago on April 4, 1949, foreign ministers from the United States and 11 countries (Belgium, Canada, Denmark, France, Iceland, Italy, Luxembourg, the Netherlands, Norway, Portugal, and the United Kingdom) gathered in Washington, DC to sign the Washington Treaty.

Also known as the North Atlantic Treaty, the treaty derives its authority from Article 51 of the United Nations Charter, which affirms the inherent right of individual or collective self-defense.

The treaty and the North Atlantic Treaty Organization’s purpose was to guarantee the freedom and security of its members through military and political cooperation following the devastating Second World War which claimed the lives of nearly 75 million people, including some 150 million wounded, and hundreds of millions more scarred by the trauma of the war. About 500,000 Americans were killed during the war and another million wounded.

After the signing of the Washington Treaty (North Atlantic Treaty), all member nations needed to ratify the agreement. The United States Senate debated the ratification from July 5th to July 8th and eventually approved the Treaty on July 21, 1949 by a vote of 83 to 13.

Two Democrats and 11 Republicans voted no; both New York Senators, Herbert Lehman (1878-1963) and Robert Wagner (1877-1953), abstained.

The treaty came into effect on October 24, 1949.

Since then, 20 more countries have joined NATO through 10 rounds of enlargement (in 1952, 1955, 1982, 1999, 2004, 2009, 2017, 2020, 2023 and 2024), a process laid out in the Treaty’s Article 10. It states that membership is open to any “European State in a position to further the principles of this Treaty and to contribute to the security of the North Atlantic area”.

Any decision to invite a country to join the Alliance is taken by the North Atlantic Council, NATO’s principal political decision-making body, on the basis of consensus among all Allies.

Seventy-five years later, NATO now has 32 member countries.

The NATO Archives are held in the NATO headquarters in Brussels, Belgium, but you can find many records relating to NATO in the US National Archives. NATO related records can be found in military, diplomatic, and legislative record groups as well as presidential records beginning with President Harry S. Truman.

Illustrations, from above: Secretary of State Dean Acheson signs the NATO Treaty on April 4, 1949, as Vice President Alben W. Barkley, left, and President Harry Truman observe (Associated Press photo); The 1949 NATO Treaty, page 3 (see a larger version at the National Archives); and President Richard Nixon addresses the North Atlantic Treaty Organization on February 24, 1969 (National Archives).