The Mongols invaded Central Europe with three armies. One army defeated an alliance which included forces from fragmented Poland and their allies, led by Henry II the Pious, Duke of Silesia in the Battle of Liegnitz. A second army crossed the Carpathian mountains and a third followed the Danube. The armies re-grouped and crushed Hungary in 1241, defeating the Hungarian army at the Battle of Mohi on April 11, 1241. The devastating Mongol invasion killed half of Hungary's population. The armies swept the plains of Hungary over the summer, and in early 1242 regained impetus and extended their control into Dalmatia and Moravia. The Great Khan had, however, died in December 1241, and on hearing the news, all the "Princes of the Blood," against Subotai's recommendation, went back to Mongolia to elect the new Khan.