On 4 April 1949, in Washington, Belgium, Canada, Denmark, France, Iceland, Italy, Luxembourg, the Netherlands, Norway, Portugal, the United Kingdom and the United States sign the North Atlantic Treaty. The Treaty enters into force on 24 August 1949.

On 4 April 1949, in Washington, Paul-Henri Spaak, Belgian Prime Minister and Foreign Minister, gives an address at the ceremony to mark the official signing of the North Atlantic Treaty.

The signing of the North Atlantic Treaty takes place on 4 April 1949 in the Grand Auditorium of the State Department in Washington. Joseph Bech, Luxembourg Foreign Minister, delivers a speech on the importance of the new military alliance.

At the signing of the North Atlantic Treaty in Washington on 4 April 1949, the US President, Harry Truman, gives an address on the importance of the future alliance and on the need to maintain peace across the world.

Map depicting the signing of the North Atlantic Treaty on 4 April 1949 in Washington and NATO's 12 founding member states. The treaty comes into force on 24 August 1949.

On 4 April 1949, in Washington, Ernest Bevin, British Foreign Minister, signs the North Atlantic Treaty.

On 4 April 1949, in Washington, Joseph Bech, Luxembourg Foreign Minister, gives an address during the ceremony to mark the signing of the agreement establishing the North Atlantic Treaty Organisation (NATO).

Robert Schuman, French Foreign Minister, after the signing of the North Atlantic Treaty, under the portrait of Lafayette at the French Embassy in Washington in April 1949.

At the signature of the North Atlantic Treaty on 4 April 1949 in Washington, Paul-Henri Spaak, Belgian Prime Minister, delivers a speech in which he stresses the importance of NATO in ensuring world peace.

US President Harry S. Truman gives an address in Washington on 4 April 1949 at the signing of the North Atlantic Treaty in which he underlines the importance that the Atlantic Alliance attaches to peace and prosperity.

On 4 April 1949, the Foreign Ministers of Belgium, Canada, Denmark, France, Iceland, Italy, Luxembourg, the Netherlands, Norway, Portugal, the United Kingdom and the United States sign the North Atlantic Treaty in Washington.

In his memoirs, Jean Chauvel, Secretary-General of the French Foreign Ministry, recalls the multilateral negotiations for the establishment of a new system of Western security. These negotiations would lead to the signing of the North Atlantic Treaty on 4 April 1949 in Washington.

On 24 August 1949, in Washington, the US President, Harry S. Truman, signs the Convention implementing the North Atlantic Treaty. Behind him, from left to right: Sir Frederick Hoyer Millar (United Kingdom), Henrik de Kauffmann (Denmark), W. D. Matthews (Canada), Louis Johnson, (US Defence Secretary), Wilhelm Munthe de Morgenstierne (Norway), Henri Bonnet (France), Pedro Theotonio Pereira (Portugal), Dean Acheson, (US Secretary of State), O. Reuchlin (Netherlands) and Mario Lucielli (Italy).

On 2 April 1951, Vincent Auriol, President of the French Republic, gives an address in Rocquencourt at the opening ceremony of the Supreme Headquarters Allied Powers Europe (SHAPE). SHAPE was set up as part of an effort to establish an integrated and effective NATO military force.

In April 1951, the Supreme Headquarters Allied Powers Europe (SHAPE) moves to its site in Rocquencourt, near Paris. It would remain at this site until 1967, when it permanently relocated to Casteau, near Mons, in Belgium.

The Protocol to the North Atlantic Treaty relating to the accession of Greece and Turkey is signed in London on 22 October 1951. On 18 February 1952, Greece and Turkey officially become members of NATO.

On 22 October 1951, in London, the Deputy Permanent Representatives of the North Atlantic Council sign the Protocol to the North Atlantic Treaty on the Accession of Greece and Turkey (who will officially become members on 18 February 1952). From left to right: Tjarda van Starkenborgh-Stachouwer (Netherlands), André De Staerke (Belgium), L. Dana Wilgress (Canada), Hervé Alphand (France), Gunnlaugur Petursson (Iceland), Soren C. Sommerfelt (Norway), M. De Steensen-Leth (Denmark), Alberto Rossi Longhi (Italy), Ruy Ennes Ulrich (Portugal), André Clasen (Luxembourg), Sir Frederick Hoyer Millar (United Kingdom) and Charles M. Spofford (USA).

"Passer en revue les troupes en carton". Le 28 février 1952, le caricaturiste britannique David Low s'interroge sur la capacité du général américain Dwight D. Eisenhower, commandant suprême des forces alliées en Europe (SACEUR), pour pallier l'infériorité numérique des forces armées européennes au sein de l'Alliance atlantique.