Around December 1240, news came that the Mongols were advancing towards Hungary. King Bela then installed front line defenses at the Carpathian Mountains, after which he returned to Buda and called a council of war and ordered unity against the Mongols. The opposite happened, however, as many of the barons were hostile towards the Cumans. The Hungarian barons noted that there were Cumans in the Mongol armies, but they didn't realize that this was because they were conscripted into it and had no say in the matter. In particular the barons didn't trust Köten, despite the fact that the Mongols had attacked his people for nearly 20 years. This chaos pushed Bela into a corner; feeling he needed to show his strength and keep the rebellious barons on his side, he ordered Köten to be placed under house arrest. This did not placate the barons and had an opposite effect of erroneously seeming to admit that the King harboured doubts about Köten, too. This angered the Cumans, who were far from happy about the actions taken against them, and who had done nothing to invite such actions and hated the Mongols. News arrived on 10 March that the Mongols had attacked the Hungarian defenses at the Carpathian passes. This prompted Bela to send a letter to Duke Frederick of Austria asking for help. Frederick had previously wanted Bela's throne, but Bela responded by amassing a vast army and marching to the gates of Vienna, which forced Frederick to step back. On 14 March, news had arrived that the Carpathian defense forces were defeated by the Mongols. Ironically, given the suspicion of the Cumans, they were the only ones who seemed willing to fight the Mongols, the memory of the fate that had befallen them on the steppes still being fresh in their minds. By this time Bela had lost control of his army and many towns were destroyed. Soon thereafter Frederick arrived, and, wishing to harm the country's defense (in revenge to Bela), he stirred up further feelings against the Cumans.