Ten years after the Nazis were defeated in World War II, West Germany formally joins the North Atlantic Treaty Organization (NATO), a mutual defense group aimed at containing Soviet expansion in Europe. This action marked the final step of West Germany’s integration into the Western European defense system.

Germany had been a divided nation since 1945. The Americans, British, and French held zones of occupation in Western Germany and West Berlin; the Soviets controlled Eastern Germany and East Berlin. Although publicly both the Americans and the Soviets proclaimed their desire for a reunited and independent Germany, it quickly became apparent that each of these Cold War opponents would only accept a reunified Germany that served their own nation’s specific interests. In 1949, the Americans, British, and French combined their zones of occupation in West Germany to establish a new nation, the Federal Republic of Germany. The Soviets responded by setting up the German Democratic Republic in East Germany.

On May 5, 1955, the American, French, and British forces formally ended their military occupation of West Germany, which became an independent country. On May 6, West Germany was officially made a member of NATO. For U.S. policymakers, this was an essential step in the defense of Western Europe. Despite the reluctance of some European nations, such as France, to see a rearmed Germany—even as an ally—the United States believed that remilitarizing West Germany was absolutely vital in terms of setting up a defensive perimeter to contain any possible Soviet attempts at expansion. The Soviet response was immediate. On May 14, 1955, the Soviet Union established the Warsaw Pact, a military alliance between Russia and its Eastern European satellites—including East Germany.

The entrance of West Germany into NATO was the final step in integrating that nation into the defense system of Western Europe. It was also the final nail in the coffin as far as any possibility of a reunited Germany in the near future. For the next 35 years, East and West Germany came to symbolize the animosities of the Cold War. In 1990, Germany was finally reunified; the new German state remained a member of NATO.