TROPPAU (Slavonic Opava), the chief town of Austrian Silesia, is a busy commercial place on the right bank of refinery and manufactories of machines and stoves. In Troppau was founded in the 13th century ; but almost its only claim to historical mention is the fact that in 1820 the monarchs of Austria, Russia, and Prussia met here to deliberate on the tendencies of the Neapolitan revolution. This congress of Troppau, however, left nearly the whole matter to be considered and decided at Laibach. The former principality of Troppau is now divided between Austria and Prussia, the latter holding the lion's share.