The Great Purge was a series of campaigns of political repression and
persecution in the Soviet Union orchestrated by Joseph Stalin in 1936–
1938. It involved a large-scale purge of the Communist Party and
Government officials, repression of peasants, Red Army leadership, and
the persecution of unaffiliated persons, characterized by widespread
police surveillance, widespread suspicion of "saboteurs",
imprisonment, and executions.

http://en.wikipedia.org/wiki/Great_Purge

An estimated 4 million people were purged between the 1920s and 1950s,
most of them in 1937 and 1938, when 1.3 million were arrested and more
than half of them executed, under the ill-famed Article 58 of the
Penal Code just about anyone could easily fall under:

“We got a painful, catastrophic inheritance from the political purges
ordered by Vladimir Lenin and Josef Stalin, when thousands of people
were killed only because the authorities thought they posed a threat
to their rule, says Alexander Brod, the director of the Moscow human
rights bureau. People were sentenced on trumped-up charges and based
on confessions made under torture."

http://english.ruvr.ru/2009/08/13/274767.html
http://www.globalmuseumoncommunism.org

"Once people figure it out, they're going to do what people everywhere
do, they're going to start protesting and they're going to start
revolting. And when that happens that's when the powers that be feel
threatened and they use the power that they have." - Jim Simpson

http://vimeo.com/13722147