The Berlin Crisis of 1961 (4 June – 9 November 1961) was the last major politico-military European incident of the Cold War about the occupational status of the German capital city, Berlin, and of post–World War II Germany. The U.S.S.R. provoked the Berlin Crisis with an ultimatum demanding the withdrawal of Western armed forces from West Berlin—culminating with the city's de facto partition with the East German erection of the Berlin Wall. The 22nd Congress of the Communist Party of the Soviet Union—the last to be attended by the Communist Party of China—was held in Moscow during the crisis.