20th August 1968: Warsaw Pact troops invade to end the Prague Spring

At around 11pm on the 20th August 1968, troops from the USSR, Bulgaria, Poland and Hungary entered Czechoslovakia in an invasion that brought the Prague Spring to an end. The invasion, known as Operation Danube, led to almost half a million soldiers crossing the border to bring Alexander Dubček's reforms to an end. The Prague Spring began in early January, shortly after Dubček became the leader of Czechoslovakia. Keen to push forward with de-Stalinisation within the country, he granted greate...