The Regency Council of Poland-Hungary negotiated peace, but the land lay without a ruler. Even with the decentralised model of government implemented by Zygmunt II the Great, the nobles struggled to surpress independence movements in Croatia, Crimea, Transylvania, Prussia, and Saxony. In the end, with no heir to be found, the council had no choice but to accept the rise of an ambitious Hungarian noble to the throne of Poland-Hungary.
Michal Korybut (rule: 1519-1521)" the Upsurper"
King of Poland-Hungary. Michal was begrudgingly crowned by the nobles, but never won the hearts of the people. He was never accepted as the rightful ruler of any of the duchies or territories beyond the ancient Polish and Hungarian borders. To boost popularity and belief in his rule, Michal started a fateful war against Mecklenburg, who had grown bloated and rich while Poland-Hungary was in disarray. When the Polish-Hungarian infantry stormed the citadel of Lübeck they found in its dungeons a starved and tortured man. That man turned out to be the long lost son of Zygmunt II.
Zygmunt III Jagiellon (rule 1521-1525) "the Scarred" "the Reformer"
King of Poland-Hungary and Bohemia, Archduke of United Prussia, Holy Roman Emperor, Duke of Lausitz, Pommern and Brandenburg, High King of Crimea, Protector of the Estonian Isles. Zygmunt III overthrew and had executed Michal Korybut after a short civil war. He then proceeded to force the Mecklenburgians into caipitualation, taking the duchy of Brandenburg and the kingdom of Bohemia. Zygmunt III saw the need to reform the empire in order to secure future stability. He rearranged a great deal of territories, absorbed the duchy of Mazovia into the kingdom of Poland, absorbed Riga into Prussia, and declared himself High King of Crimea. He also turned the margraviate of Pommern into a duchy, and merged the margraviate of Neumark into the duchy of Brandenburg. Having seen that the future lay in Germany rather than Russia, Zygmunt III did not revive the Polish-Lithuanian alliance that had been canceled under MIchal Korybuts rogue rule. When the king of Munster finally kicked the bucket, Zygmunt III was proclaimed Holy Roman Emperor. Once more the imperial crown lay safe in Jagiellon hands. Zygmunt III enjoyed a popular, though brief reign, passing away from his war injuries in 1525, leaving the throne to his son Stanislaw, who also had been recovered from Mecklenburgian captivity.
Stanislaw II Jagiellon (rule: 1525-1540) "the Crusader"
King of Poland-Hungary and Bohemia, Archduke of United Prussia, Holy Roman Emperor, Duke of Lausitz, Pommern and Brandenburg, High King of Crimea, Protector of the Estonian Isles, the one before whom the unbelievers tremble. Stanislaw II continued his father's policy of stability before territorial expansion. Like Aleksander I, he was a very pious man, and shared a close friendship with several popes and bishops. Stanislaw II began the arduous work of converting Russian Orthodox Christians and Muslims to the Catholic faith. He also fought several wars to stop the cancerous spread of Protestantism in Germany and Scandinavia. When simply purging the heretics proved unfruitful, Stanislaw II made them his vassals, so that they could do no serious harm. Stanislaw II also worked to build an extensive network of allies in Central Europa, and this caused conflict with the Habsburgs of Austria.