 Complete the following phrase:  Sigismund Korybut began negotiations with Sigismund of Hungary, with an intention to reconcile the Catholics and Hussites. However, his political career came to an end in 1427, when by the initiative of suspicious Prague Taborites, he was imprisoned in Valdštejn Castle for the organization of a revolt in Prague. After release from prison in 1428, Sigismund participated in Taborite battles in Silesia. The decisive loss in the 