Augustus III (1696 - 1763) was the only legitimate son of Augustus II the Strong, King of Poland and Grand Duke of Lithuania. He inherited the duchy of Saxony (as prince-elector Frederick Augustus II) upon his father's death in 1733. With the support of troops sent from the Russian Empire and Holy Roman Empire, he was elected King of Poland and Grand Duke of Lithuania by a minority of electors in late 1733, and was crowned in 1734, becoming the second and last Wettiner to occupy the Polish throne. Augustus III's installation with the aid of foreign troops was the inciting event of the War of Polish Succession, which involved numerous European powers who wished to expand their spheres of control. This war ended with the Treaty of Vienna in 1738 which confirmed Augustus III as King of Poland but offered concessions to the rival claimant to the throne, Stanisław Leszczyński.
Augustus III spent less than three years of his thirty-year reign living in Poland, residing instead in Dresden Castle in Saxony. He delegated the management of the Polish-Lithuanian Commonwealth to his Prime Minister, Heinrich von Brühl. Under Augustus III, Poland was involved in the War of Austrian Succession and the Seven Years' War, aligned with Austria against Prussia in both conflicts. It was during the Seven Year's War, when Prussia occupied Saxony, that Augustus III was forced to briefly flee to Poland. Augustus III was a patron of the arts, adding many artworks to Dresden Castle, and appointed Johann Sebastian Bach as his court composer in 1736.
Augustus III married Maria Josepha of Austria, daughter of Holy Roman Emperor Joseph I in 1719, after seven years of negotiations and Augustus III's conversion to Catholicism. They had fifteen children together. One of his daughters, Maria Josepha of Saxony, was the mother of three French kings: Louis XVI, Louis XVIII, and Charles X. Another daughter, Maria Amalia of Saxony, became Queen Consort of Spain. Augustus III's eldest surviving son, Frederick Christian of Saxony, succeeded him as Elector of Saxony but died of smallpox after a reign of only 74 days.
By the time of Augustus III's death in 1763, Russian influence over Polish affairs had strengthened, and Russian support had shifted to Stanisław August Poniatowski, a lover of Catherine the Great. The Russians instituted a coup which resulted in Poniatowski being elected King of Poland in 1764. Augustus III's legacy is considered to be one of diminishing power and influence of the Polish-Lithuanian Union, and increased internal disorder. By 1772, the Polish-Lithuanian Commonwealth had weakened to the point that it became a Russian protectorate and its territory was partitioned between Russia, Prussia, and Austria.
Source: Britannica Online Encyclopedia