How did nationalism end the Cold War?

What ultimately caused the collapse of communism in Eastern Europe? Was it a revival of nationalist sentiment, a failure of Soviet central economic planning to provide comparable lifestyles to those in Western Europe, or was it a fundamental failure of communism to integrate itself into Eastern Europe? These issues span different countries, each with their own individual histories. All, however, ultimately acted to the same ends in a relatively uniform period of time to achieve the same result, a result which ended the last European empire of the modern era.