In Mommsen's view, the decisive issue was whether the Federal Republic was a continuation of the "Reich" that had existed from 1871 to 1945 or not. He argued that at first the continuity thesis dominated, as shown by the lavish celebrations of the 150th anniversary of Bismarck's birthday in 1965, but as a younger generation came of age, a more critical attitude towards the past emerged. He wrote further that German reunification "would presume the collapse of the Soviet empire, a premise unthinkable at the time". As a result, since German reunification was impossible in the 1950s-60s, together with the resumption of Germany as a great power, led West Germans to embrace the idea of integration into the European Economic Community and NATO as the best substitutes. Adenauer's policies of integration into the EEC and NATO suggested that the only role possible for the Federal Republic was at best as a middle-size world power whose influence stemmed from working with other Western powers. The policies of Western integration caused the idea of a continuity of German history to lose its appeal to the younger generation of West Germans, he wrote, leading to the idea popular by the late 1960s that the state founded in 1949 represented discontinuity.