CZASLAU, a town of Bohemia, situated near the left bank of an affluent of the Elbe, 48 miles E.S.E. of Prague. The church is surmounted by a lofty spire, and contains the tomb of the celebrated Hussite leader Ziska, who died in 1424. Here Frederick the Great defeated the Austrians, May 17, 1742. Pop. about 4000.