A canon of Breslau, St. Hyacinth joined the Dominican Order in Rome during the lifetime of the founder, in about the year 1217. He returned to Cracow with the first band of Dominican missionaries. The newcomers spread over all the northern countries into Russia, the Balkans, Prussia and Lithuania. St. Hyacinth preached the crusade against the Prussians. He died on the feast of the Assumption, 1257.