The Hungarian Uprising

In 1945, USSR installed puppet government in Hungary; designed to remove opposition and enforce loyalty. As a result many protest groups emerged striving for democracy.
In February 1956, Krushchev criticised parts of Stalin's rule and began a policy of 'destalinisation' a policy that would move away from Stalin's corrupt and aggressive ideals. Hungary saw this as an opportunity to move away from their Communist foundations and begin a more liberal movement.
Imry Nagy
In 1956 the Communist dictatorship was overthrown and a new, more liberal leader was introduced; Imry Nagy. He made obvious signs of moving away from the previous Communist government by re-introducing things such as free criticism of the government and disbanding the AVH. Kruschev did not want to lose countries such as Hungary from the Sovet Sphere of influence and saw this new leader as a threat to the Soviet Empire.
Soviet Invasion
On the 4th November 1956, Krushchev orders Red Army to take control. Tanks and soldiers enter the capital of Budapest and were met with opposition in the streets. Eventually the Communist leadership was restored.
The Plea for Help
The opposition leaders were all captured and executed along with Imry Nagry. There were several desperate pleas over the radio for US assisstance but there was no US intervention.
Around 30,000 Hungarians died during the invasion. The invasion put out a message to any other satellite states that revolution was not an option and the fact that the US did not get involved would of pleased the USSR.