Adolf Hitler ruled Germany from 1933 until he committed suicide in 1945.  Joseph Stalin ruled the Soviet Union from 1924 until his death in 1953.  Between 1933 and 1945 these two brutal dictators oversaw the killing of 14 million noncombatants in the region comprised of the Baltic states, Belarus, Poland, and Ukraine.  Timothy Snyder explains how and why the NAZI and Soviet regimes inflected such suffering in Bloodlands: Europe Between Hitler and Stalin.