The War of the Polish Succession (1733–1738) was a major European war for princes' possessions sparked by a Polish civil war over the succession to Augustus II, King of Poland that other European powers widened in pursuit of their own national interests. France and Spain, the two Bourbon powers, attempted to check the power of the Austrian Habsburgs in western Europe, as did the Kingdom of Prussia; whilst Saxony and Russia mobilized to support the eventual Polish victor. The slight amount of fighting in Poland resulted in the accession of Augustus III, who in addition to Russia and Saxony, was politically supported by the Habsburgs.
The war's major military campaigns occurred outside Poland. The Bourbons, supported by Charles Emmanuel III of Sardinia, moved against isolated Habsburg territories. In the Rhineland France successfully took the Duchy of Lorraine, and in Italy Spain regained control over the kingdoms of Naples and Sicily (lost in the War of the Spanish Succession), while territorial gains in northern Italy were limited despite bloody campaigning. Great Britain's unwillingness to support Habsburg Austria demonstrated major cracks in the Anglo-Austrian Alliance and may have contributed to Austria's military failures.
Although a preliminary peace was reached in 1735, the war was formally ended with the Treaty of Vienna (1738) in which Augustus III was confirmed as king of Poland and his opponent Stanislaw I (who had received virtually no foreign military support) was awarded the Duchy of Lorraine. Francis Stephen, the duke of Lorraine, was given the Grand Duchy of Tuscany in compensation for the loss of Lorraine. The Duchy of Parma went to Austria whereas Charles of Parma took the crowns of Naples and Sicily, resulting in territorial gains for the Bourbons. Poland also gave up claims to Livonia and direct control over the Duchy of Courland and Semigallia, which, although remaining a Polish fief, was not integrated into Poland proper, and came under strong Russian influence.