CZASLAU, or CASLAU, a town of Bohemia, the chief place of the circle of the same name, situated near the left bank of an affluent of the Elbe, in a fertile plain 48 miles E.S.E. of Prague, on the North-west Railway from Vienna. The church is surmounted by a lofty spire, the highest in Bohemia, and contains the tomb of the celebrated Hussite leader Ziska, who died in 1424. Here (or more accurately at the village of Chotusitz, 2i miles north of this) Frederick the Great defeated the Austrians, May 17, 1742. Population in 1869, 5998, chiefly agriculturists.