Son of Augustus III of Poland and Maria Josepha of Austria. In 1765 he married, secretly, Maria Chiara Spinucci (d. 1792), a Lady-in-waiting to his sister-in-law. Their marriage wasn't formally proclaimed until 1777.
Following the death of his older brother Frederick Christian in 1763, Prince Xavier acted as administrator of the electorate of Saxony on behalf of his nephew Frederick Augustus (1750-1827) until his coming-of-age in 1768.1 In 1769 he moved to France where he received the title of Count of Lusatia. At the beginning of the French revolution, he and his family moved to Rome, where he stayed until a few years after the death of his wife 1792. He returned to Saxony and spent the rest of his life in Schloss Zabeltitz where he died in 1806.
- 1The Dowager Electress Maria Antonia (1724-1780) acted an actual regent during that same period.
Boswell visited the Court of Saxony in Dresden on October 12, 1764, and subsequently described Xavier as having
something the look of Dempster.