Augustus III of Poland

Born the only legitimate son of Augustus the Strong, he converted to Catholicism in 1712 to position himself for the Polish throne. After marrying Maria Josepha of Austria in 1719, he became Elector of Saxony in 1733 and secured the Polish crown that same year through Russian backing and recognition from Charles VI - crowned in Kraków in January 1734 after banishing his predecessor Stanisław I. His reign delivered two military disasters: siding with Austria against Prussia in the War of Austrian Succession and the Seven Years' War left Saxony defeated and occupied both times. In Poland, he handed real power to the Czartoryski and Poniatowski families while Catherine the Great meddled freely in Polish affairs, deepening the country's dependence on Russia, Prussia, and Austria. He delegated Saxon and Polish administration entirely to his chief adviser Heinrich von Brühl, spending three decades more interested in ease and patronage of the arts than governance. When he died in 1763, Russia blocked his family's succession and installed Stanisław August Poniatowski - Catherine's lover - ensuring the throne passed exactly where Augustus had let control drift all along.