Casimir III the Great, b 30 April 1310, d 5 November 1370. Polish king from 1333, last of the Piast dynasty. Casimir began the expansion of Poland into Ukrainian territory (Chervona Rus’). Having made peace on his western border with Bohemia and the Teutonic Knights, Casimir obtained the support of Hungary and the neutrality of the Tatars. In 1340, following the death of Prince Yurii II Boleslav, Casimir invaded Galicia, taking Lviv and destroying its fortifications. He was repelled by the boyars under the leadership of Dmytro Dedko, but, on Dedko's death in 1349, Casimir seized Galicia and western Volhynia, consolidating his rule in wars against Lithuania's Prince Liubartas. Casimir distributed property and privileges in Galicia to Polish magnates, provided incentives to Polish merchants and German colonists, and granted cities and towns—especially Lviv—self-government on the German model. He supported Catholic missionary orders, particularly the Franciscans and Dominicans, though he did not persecute the Orthodox and agreed to reinstate the Halych metropoly.
Encyclopedia of Ukraine