(1917-1936) Communism brings hope--and horrors--to Russia's millions.
(1942-1987) Nuclear energy unleashes unprecedented destruction--and the hope for cheap power.
(1945-1962) A "cold" war embroils the U.S. and the Soviet Union in a contest of ideologies.
(1949-1977) Chinese citizens zealously follow Chairman Mao's revolutionary dictums.
(1954-1981) Revolutionaries use the power of guerrilla warfare in Cuba, Vietnam, and Afghanistan.
(1980-1993) Communist rule crumbles in the Soviet Union as people find the courage to speak out.