I took the image above at the central Wenceslas Square in Prague today. The poster in the bottom right is from 21st of August 1968.

There was an attempt by the Czechoslovakian communist party to do Socialism with a human face and reform the country. But today 40 years ago tanks from Soviet and other Warsaw Pact countries intervened and rolled into Czechoslovakia and successfully crushed what is known now as the Prague Spring.

Helge and Pavel have written more on the Prague Spring and Pavel provides a level-headed reflection from a Czech on the events:

I look opon socialism with a human face and Dubceks reforms with the same distance as people in the West look upon hippies. […] The political messages during Dubceks time was also on thin ice – socialism and democracy, sovereignty and friendship with the Soviet Union, democracy and a one-party-government. A true Czech stew dish of everything. Prague Spring as a fight for freedom is a myth. (my translation)

Read their original post on Prag Foråret or an English translation.