Excerpts from Books and Wikipedia
"The workers uprising against communist rule in East Germany in June 1953 was the first of several similar outbreaks--Hungary in 1956, Czechoslovakia in 1968, and Poland in 1970--that demonstrated discontent with Soviet-style puppet states in Eastern Europe. . . . The authorities reacted quickly and brutally, ordering 16 Soviet army divisions (20,000 men) and 10,000 East German 'People's Police' (Volkspolezei) to crush the revolt by any means. . . . Coming only three months after Stalin's death and while the struggle to fill the power vacuum was still in progress in Russia, the Berlin uprising badly shook the leaders of the German Democratic Republic. Repression was their answer--leading to a brain drain to the West and the building of the Berlin Wall in 1961." [Furtado: 1001 Days]