The Prague Spring (Czech: Prask jaro, Slovak: Prask jar) was a period of political liberalization and mass protest in

the Czechoslovak Socialist Republic. It began on 5 January 1968, when reformist Alexander Dubek was elected First Secretary of the Communist Party of Czechoslovakia (KS), and continued until 21 August 1968, when the Soviet Union and other Warsaw Pact members invaded the country to suppress the reforms.

The Prague Spring reforms were a strong attempt by Dubek to grant additional rights to the citizens of Czechoslovakia in an act of partial decentralization of the economy and democratization. The freedoms granted included a loosening of restrictions on the media, speech and travel. After national discussion of dividing the country into a federation of three republics, Bohemia, Moravia-Silesia and Slovakia, Dubek oversaw the decision to split into two, the Czech Socialist Republic and Slovak Socialist Republic. This dual federation was the only formal change that survived the invasion.

The reforms, especially the decentralization of administrative authority, were not received well by the Soviets, who, after failed negotiations, sent half a million Warsaw Pact troops and tanks to occupy the country. The New York Times cited reports of 650,000 men equipped with the most modern and sophisticated weapons in the Soviet military catalogue. A massive wave of emigration swept the nation. Resistance was mounted throughout the country, involving attempted fraternization, sabotage of street signs, defiance of curfews, etc. While the Soviet military had predicted that it would take four days to subdue the country, the resistance held out for eight months until diplomatic maneuvers finally circumvented it. It became a high-profile example of civilian-based defense; there were sporadic acts of violence and several protest suicides by self-immolation (the most famous being that of Jan Palach), but no military resistance. Czechoslovakia remained controlled by the Soviet Union until 1989, when the Velvet Revolution peacefully ended the communist regime; the last Soviet troops left the country in 1991.

After the invasion, Czechoslovakia entered a period known as normalization (Czech: normalizace, Slovak: normalizcia), in which new leaders attempted to restore the political and economic values that had prevailed before Dubek gained control of the KS. Gustv Husk, who replaced Dubek as First Secretary and also became President, reversed almost all of the reforms. The Prague Spring inspired music and literature including the work of Vclav Havel, Karel Husa, Karel Kryl and Milan Kundera's novel The Unbearable Lightness of Being.

Alexander Dubček (Slovak pronunciation: [ˈaleksander ˈduptʂek]; 27 November 1921 – 7 November 1992) was a Slovak politician who served as the First Secretary of the Presidium of the Central Committee of the Communist Party of Czechoslovakia (KSČ) (de facto leader of Czechoslovakia) from January 1968 to April 1969. He attempted to reform the communist government during the Prague Spring but was forced to resign following the Warsaw Pact invasion in August 1968.

During his leadership, under the slogan "Socialism with a human face", Czechoslovakia lifted censorship on the media and liberalized Czechoslovak society, fueling the so-called New Wave in Czechoslovak filmography. However, he was put under pressure by Stalinist voices inside the party as well as the Soviet leadership, who disliked the direction the country was taking and feared that Czechoslovakia could loosen ties with the Soviet Union and become more westernized. As a result, the country was invaded by four other Warsaw Pact countries on 20–21 August 1968, ending the Prague Spring. Dubček resigned in April 1969 and was succeeded by Gustáv Husák, who initiated normalization. Dubček was then expelled from the Communist Party in 1970.

Later, after the Velvet Revolution (the dismantling of the communist government in 1989), he was Chairman of the federal Czechoslovak parliament. Also in 1989, the European Parliament awarded Dubček the Sakharov Prize.