 A notable magnate and military commander with Ruthenian and Romanian origin , Wiśniowiecki was heir of one of the biggest fortunes of the state and rose to several notable dignities , including the position of voivode of the Ruthenian Voivodship in 1646 . His conversion from Eastern Orthodoxy to Roman Catholicism caused much dissent in Ruthenia and Ukraine ( parts of the Polish – Lithuanian Commonwealth ) . Wiśniowiecki was a successful military leader as well as one of the wealthiest magnates of Poland , ruling over lands inhabited by 230 @,@ 000 people . 
