The Czechoslovakia Crisis of 1968 was a watershed moment in Cold War. The Soviet-led invasion and subsequent occupation marked the beginning of the end for the Czechoslovak reform movement known as the "Prague Spring."
The "Prague Spring," was a reform movement had been brewing for years, fed by economic problems as well as growing demands from Communist intellectuals for more freedom and pluralism within a socialist system. But it really gathered steam at the beginning of 1968, in January, when the Czechslovak Communist Party's Central Committee replaced its hard-line First Secretary Antonin Novotny with the moderate reformer Alexander Dubcek, who eventually sided more and more clearly with the forces for change.