The War of the Polish Succession (1733-1738) was a European war and a Polish civil war, with considerable interference from other countries, to determine the succession to Augustus II, King of Poland.
Former Polish king Stanislas I, ousted during the Great Northern War sought to return to power and had behind him the ethnic Polish nobility, France, Spain, and the Kingdom of Sardinia. Augustus III, Elector of Saxony and son of Augustus II, was supported by the Lithuanian nobility of Poland, and by Russia and Austria.
The war opened in 1733 with an invasion of Poland by Russia, which quickly took Warsaw and forced the election of Augsutus as king by the portion of the Sejm that could be assembled. Stanislas was pushed into the north of the country where, backed by Polish and French forces, he held out for six months against the Russians and Saxons. He then left Poland entirely.
From then on, the war within Poland degenerated into one between Poles and Lithuanians over who was to be monarch, while outside the country the French occupied Lorraine, Austria fought France and Sardinia in northern Italy, while also, along with Saxony and a few other German states holding on grimly against the French in the Rhineland. In May 1734 Austria's defeat by the Spanish at the Battle of Bitonto opened the kingdom of Naples to Spanish conquest.
A preliminary peace was concluded in October 1735 and ratified in the Treaty of Vienna (November 1738). Augustus was confirmed as king of Poland, Stanislas being compensated with the Duchy of Lorraine for the duration of his lifetime, while the former duke of Lorraine was made heir to the dukedom of Tuscany. The Infant Charles of Spain was confirmed as king of Naples and Sicily, with the Austrians being compensated by the acquisition of Charles's Duchy of Parma, and by the other powers' recognition of the Pragmatic Sanction that would allow Emperor Charles's daughter Maria Theresa to succeed him. France was the most successful of the extra-Polish combatants in the long run - lost to France after the War of the Grand Alliance, Lorraine was now to return to the French crown upon Stanislas' death, which occurred in 1766.