In 1956, Khrushchev, then-General Secretary of the Communist Party of the Soviet Union, took the approach of "de-Stalinization". This caused quite a turbulence in the communist world; many countries' Communist Party systems began to be criticized. By 1967, divisions had begun to appear in the top ranks of the Czechoslovak Communist Party. Antonín Novotný, who was the First Secretary and President, was challenged by reformist leader Alexander Dubček and others. On January 5, 1968, Dubček replaced Novotný as First Secretary of the Communist Party of Czechoslovakia.

After Dubček took office, in the "Action Program for the Communist Party of Czechoslovakia" that was adopted in April 1968, he proposed "socialism with a human face". This would include promoting liberalization of speech and artistic activities, introducing market mechanisms, carrying out economic reforms, strengthening economic relations with Western countries, etc. Dubček declared that he wanted to create "a free, modern, and highly humanistic society" in a series of political reforms that came to be known as the Prague Spring.

In this political climate, the Czech people were bursting with political enthusiasm. Students, intellectuals, and workers took to the streets in their numbers, fighting for democracy and calling for change. They showed unprecedented radicalism and revolutionary zeal, exceeding even the expectations of the reformers. However, the Communist Party of the Soviet Union saw it as a threat to its dominance, fearing that all of Eastern Europe would be stirred. On August 21, 1968, the Soviet Union invaded Czechoslovakia by force, ending the Prague Spring and beginning a period of oppression.

Reference Materials: [端傳媒 (Initium Media)(Chinese)] (https://theinitium.com/article/20180730-opinion-zhangyueran-praguespring/); [紐約時報中文網(New York Times Chinese Edition)(Chinese)] (https://cn.nytimes.com/world/20180821/prague-spring-communism/zh-hant/); [法國國際廣播電台 (Radio France Internationale)(Chinese)] (https://www.rfi.fr/tw/政治/20180822-捷克民眾上街紀念布拉格之春50周年-抗議現政府與共產黨合作)