The Slovak communist party was founded in 1921 but was soon incorporated into the Chechoslovak communist party. As Red Army troops marched into Chechoslovakia in 1944-45, the Communists returned to Slovakia and came to power after a 1948 coup. To curb any opposition, the Communist authorities launched a wave of terror. More than 20.000 people were arrested by the NKVD and deported to Siberia. The Communist authorities of Slovakia imprisoned 27.000 people on political grounds during 1948-1952 and another 70.700 were thus sentenced during 1953-1967. Some 186.000 persons served time in labor camps. At least 15.726 died in imprisonment and 238 were executed. The terror caused at least 450.000 people to flee to the West and another 60.000 emigrated later, using legal means.