Although Alexander Dubček subsequently became the chief reformer, he was not particularly qualified for this role. He was a young Slovak who made his way into politics through the party apparat. People did not expect much from him, and for a month nothing seems to have happened. As the representative of a new generation, Dubček must have felt frustrated with the Novotný type of apparatchiks, and, though he was in power, he did not control the apparat. That is probably why he decided on an experiment rather than the time-honoured purge techniques. His way of getting rid of the old guard was to subject them to the pressure of public opinion. Once he had made this vital decision, many reforms followed. By April the apparat was Dubček's. Several diehards preferred suicide to disgrace, but Novotný and many others resigned only after a hard struggle. There was a new premier, Oldřich Čḥİník, and Šik and Husák became vice premiers in charge of reforms in, respectively, the economy and Slovakia. Czechoslovakia also had a new president (from March 30), Ludvík Svoboda, who had been purged in the 1950s and had lived in retirement since then. The Ministry of the Interior was under the control of another purge victim, Josef Pavel. The newly elected Presidium of the Communist Party consisted largely of newcomers, and the Action Program was compiled by young party intellectuals.

The Action Program, adopted by the Central Committee on April 5, embodied the reform ideas of the several years preceding, and it accepted the connection between economic and political reform. Among its most important points were a new autonomy for the Slovaks (federation); industrial and agricultural reforms, so long overdue; a revised constitution that would guarantee civil rights and liberties; and complete rehabilitation of all citizens whose rights had been infringed in the past. The program also envisaged a strict division of powers: the National Assembly, not the Communist Party, would be in control of the government, which in turn would become a real executive body and not a party body; courts were to become independent and act as arbiters between the legislative and executive branches. The Communist Party would have to justify its leading role by competing freely for supremacy with other forces in elections. This democratization of life in the country also would extend to the party, in which all offices would be elective. Dubček claimed that he was offering “socialism with a human face.”

The effect that all these happenings had on the Czechoslovak public was unprecedented and quite unexpected. With freedom of the press reestablished, there was a revival of interest in alternative forms of political organization. There were even efforts to reestablish the Social Democratic Party, fused forcibly with the Communist Party in 1948. With the collapse of the official communist youth movement, youth clubs and the Boy Scout movement were resurrected. The Christian churches became active as unexpectedly as did many long-forgotten societies, national minority associations, and human-rights movements.

On June 27 there appeared in Literární listy (“Literary Gazette”) a document written by Ludvík Vaculík and signed by a large number of people representing all walks of Czechoslovak life. This was the “Two Thousand Words,” urging even more rapid progress to real democracy. Dubček—not to mention the Soviet Union and the other Warsaw Pact allies (with the exception of Romania)—became apprehensive, but, though shocked by the proclamation, Dubček remained convinced that he could control the transformation of Czechoslovakia. The Soviet Union, however, began to take a different view. The Czechs and Slovaks failed to comprehend the hostility of the reaction to the “Two Thousand Words,” particularly by the Soviet Union, Poland, and East Germany. Dubček declined an invitation to participate in a special meeting of the Warsaw Pact powers, which on July 15 sent him a letter saying that his country was on the verge of counterrevolution and that they considered it their duty to protect it. To the last, Dubček remained confident that he could talk himself out of any difficulties with his communist neighbours. He accepted an invitation by Brezhnev to a conference at Čierná-nad-Tisou (a small town in Slovakia), where the Soviet Politburo and the Czechoslovak leaders tried to resolve their problems. On August 3, representatives of the Soviet, East German, Polish, Bulgarian, Hungarian, and Czechoslovak Communist parties met at Bratislava; the communiqué issued after the meeting, while loosely written, gave the impression that pressure would be eased on Czechoslovakia in return for somewhat tighter control over the press.

On the evening of August 20, however, Soviet, East German, Polish, Hungarian, and Bulgarian armed forces invaded the country and occupied it with little opposition. Politically, the invasion was a catastrophe. The Soviet authorities seized Dubček, Černík, and several other leaders and took them to Moscow but failed to produce alternative party and state leaders acceptable to the people. The population reacted against the invasion with passive resistance and improvisation (e.g., road signs were removed so that the invading troops would get lost). Communications were disrupted, supplies were held up, and the country was almost leaderless, but life went on as if the occupation forces were not there. Even the scheduled 14th Communist Party Congress took place on August 22 and elected a pro-Dubček Central Committee and Presidium—the very thing the invasion had been timed to prevent. The National Assembly (declaring its loyalty to Dubček) continued its plenary sessions. On August 23 President Svoboda, accompanied by Husák, left for Moscow to negotiate a solution. The negotiations were concluded on August 27, and Svoboda, bringing with him Dubček, Černík, and Smrkovský, returned to Prague to tell the Czechs and Slovaks what price they would have to pay for their socialism with a human face: Soviet troops were going to stay in Czechoslovakia, and the leaders had agreed to tighter controls over political and cultural activities.

The presence of Soviet troops helped the hardliners defeat Dubček and the reformers. First of all, the 14th party congress was declared invalid, as required by the Moscow Protocol agreed upon on August 26. Thus, the hardliners remained in positions of power and, by using Soviet pressure and divisions among the reformers, ultimately achieved their victory. In the meantime Czechoslovakia became a federal republic, the Czech Lands (Bohemia and Moravia) and Slovakia becoming the Czech Socialist Republic and the Slovak Socialist Republic, respectively, with national parliaments and governments. The Czech and Slovak people, however, were more impressed by the suicide of Jan Palach—a student who in January 1969 set himself afire in protest against infringements of national independence—than by Dubček's declarations that the revival movement was going on as before the invasion. Gradually Dubček either dismissed his friends and allies or forced them to resign, until he found himself isolated.

This slow rise of the hardliners and of the “realists” (among whom was Husák) culminated on April 17, 1969, when Dubček was removed as first secretary after anti-Soviet rioting in Czechoslovakia. Dubček was replaced by Husák, who promptly declared the Dubček experiments to be finished and proposed a process that he called “normalization.”