When Mikhail S. Gorbachev (1931-) became general secretary of the Communist Party of the Soviet Union in March 1985, he launched his nation on a dramatic new course. His dual program of “perestroika” (“restructuring”) and “glasnost” (“openness”) introduced profound changes in economic practice, internal affairs and international relations. Within five years, Gorbachev’s revolutionary program swept communist governments throughout Eastern Europe from power and brought an end to the Cold War (1945-91), the largely political and economic rivalry between the Soviets and the United States and their respective allies that emerged following World War II. Gorbachev’s actions also inadvertently set the stage for the 1991 collapse of the Soviet Union, which dissolved into 15 individual republics. He resigned from office on December 25, 1991.