from 1960 to 1989 became the Czechoslovak Socialist Republic, and while they fought all religions, Catholicism was targeted with particular aggressiveness. After the Velvet Revolution in 1989 and the restoration of democracy in the Czech lands, Catholicism, like other forms of Christianity, did not recover and continued to lose adherents. The data from the national censuses show that Catholics decreased from 76.7% of the Czechs in 1950 prior to the communist period, to 39.1% in 1991 after the fall of communism, to 26.9% in 2001, to 10.5% in 2011, and to 9.3% in 2021. Protestantism In the late 14th century, the religious and social reformer Jan Hus started a Proto-Protestant movement which would have been later called "Hussitism" after him. Although Jan Hus was declared heretic by the Catholic Church and burnt at the stake in Constance in 1415, his followers seceded from the Catholic Church and in the Hussite Wars (1419–1434) they defeated five crusades organised against them by the Holy Roman Emperor Sigismund. Petr Chelčický continued in the wake of the Bohemian Hussite Reformation and gave rise to the Hussite Moravian Church. During the 15th and 16th century, most of Czechs were adherents of Hussitism, and at the same time many Sudeten Germans of the Czech lands joined the Protestant Reformation of Martin Luther and his doctrine (Lutheranism). After 1526, Bohemia came increasingly under the control of the Habsburg monarchy, as the Habsburgs became first the elected and later the hereditary rulers of Bohemia. The Defenestration of Prague and the subsequent revolt against the Habsburgs in 1618 marked the start of the Thirty Years' War, which quickly spread throughout Central Europe. In 1620, the rebellion in Bohemia was crushed at the Battle of White Mountain, and the ties between Bohemia and the Habsburgs' hereditary lands in Austria were strengthened. The war had a devastating effect on the local population, and the people were forced to convert back to Catholicism under the Habsburgs' Counter-Reformation efforts. In 1918, when the Habsburg monarchy disintegrated and independent Czechoslovakia emerged, most of the Czechs professed formal affiliation to Catholicism; anti-Catholic sentiments spread quickly as Catholicism was viewed as the religion re-imposed by the Habsburg, so that in 1920 the Czechoslovak Hussite Church split off the Catholic Church and was joined by about 10% of the former Catholic clergy, and 10.6% of the Czechs had become again Hussites by 1950. The Czechoslovak Church was