An era ended when the Soviet Union collapsed on Dec. 31, 1991. The confrontation between the United States and the Soviet Union defined the Cold War period. The collapse of Europe framed that confrontation. After World War II, the Soviet and American armies occupied Europe. Both towered over the remnants of Europe’s forces. The collapse of the European imperial system, the emergence of new states and a struggle between the Soviets and Americans for domination and influence also defined the confrontation. There were, of course, many other aspects and phases of the confrontation, but in the end, the Cold War was a struggle built on Europe’s decline.