Without the consent of the Soviet Union, German unity would not have been possible. And certainly not without Mikhail Gorbachev, the general secretary of the CPSU. But how did this happen? Why did Gorbachev not only give unity to the Germans, but also leave a united Germany in NATO? For the first time, a comprehensive German-language study of the negotiations of 1989/90 between the two German states, the three Western powers and the Soviet Union, is available here, which provides answers to all relevant questions. It turns out that the Soviet leader had not only recognized that the entire alliance system was outdated, and that he needed new structures to make his country an attractive partner of the West. Gorbachev came up with startling proposals that are still very worthy of discussion today.