Warsaw Pact invasion of Czechoslovakia
On 20–21 August 1968, the Czechoslovak Socialist Republic was jointly invaded by four fellow Warsaw Pact countries: the Soviet Union, the Polish People's Republic, the People's Republic of Bulgaria, and the Hungarian People's Republic. The invasion stopped Alexander Dubček's Prague Spring liberalisation reforms and strengthened the authoritarian wing of the Communist Party of Czechoslovakia (KSČ).
Source: Wikipedia
Text is available under the Creative Commons Attribution-ShareAlike License; additional terms may apply.