The Prague Spring (, ) was a period of political liberalization in Czechoslovakia during the era of its domination by the Soviet Union after World War II. It began on 5 January 1968, when reformist Alexander Dubček was elected First Secretary of the Communist Party of Czechoslovakia, and continued until 21 August when the Soviet Union and all members of the Warsaw Pact, with the notable exception of Romania, invaded the country to halt the reforms.