Stanisław II August (born Stanisław Antoni Poniatowski; 17 January 1732 – 12 February 1798), known also by his regnal Latin name Stanislaus II Augustus, and as Stanisław August Poniatowski (Lithuanian: Stanislovas Augustas Poniatovskis), was King of Poland and Grand Duke of Lithuania from 1764 to 1795, and the last monarch of the Polish–Lithuanian Commonwealth.
Born into wealthy Polish aristocracy, Poniatowski arrived as a diplomat at the Russian imperial court in Saint Petersburg in 1755 at the age of 22 and became intimately involved with the future empress Catherine the Great. With her aid, he was elected King of Poland and Grand Duke of Lithuania by the Sejm in September 1764 following the death of Augustus III. Contrary to expectations, Poniatowski attempted to reform and strengthen the large but ailing Commonwealth. His efforts were met with external opposition from neighbouring Prussia, Russia and Austria, all committed to keeping the Commonwealth weak. From within he was opposed by conservative interests, which saw the reforms as a threat to their traditional liberties and privileges granted centuries earlier.
