Today is Tuesday, Aug. 20, the 233rd day of 2024. There are 133 days left in the year. Today in history: On Aug. 20, 1968, the Soviet Union and other Warsaw Pact nations invaded Czechoslovakia to crush the “Prague Spring” liberalization movement. Also on this date: In 1858, Charles Darwin’s theory of evolution was first published, in the “Journal of the Proceedings of the Linnean Society”. Related Articles Today in History: August 19, last U.S.