Anti-Polish rhetoric combined with the condemnation of Polish culture was most prominent in the 18th-century Prussia during the partitions of Poland. However, anti-Polish propaganda begins with the Teutonic Order in the 14th century. It was a very important tool in the Order's attempt to conquer the Duchy of Lithuania which eventually failed because of Lithuania's Personal union with the Crown of the Kingdom of Poland and the Christianization of Lithuania to Catholicism. The first major thinker to openly call for the genocide of the Polish people was the 14th century German Dominican theologian Johannes von Falkenberg who on behalf of the Teutonic Order argued not only that Polish pagans should be killed, but that all Poles should be subject to genocide on the grounds that Poles were an inherently heretical race and that even the King of Poland, Jogaila a Christian convert, ought to be murdered. The assertion that Poles were heretical was largely politically motivated as the Teutonic Order desired to conquer Polish lands despite Christianity having become the dominant religion in Poland centuries prior.