The Treaty of the Three Black Eagles, or Treaty of Berlin, was a secret treaty signed in September and December 1732 between the Habsburg monarchy, the Russian Empire and Prussia.
It concerned the joint policy of the three powers regarding to the succession of the Polish throne in light of the expected death of King Augustus II of Poland (and Elector of Saxony from the House of Wettin) and the Polish custom of royal elections. It intended to exclude the candidacies of Augustus' son, Frederick Augustus, and of Stanislas Leszczynski, who had already been king of Poland from 1704 to 1709.
However, in 1733, as Stanislaus was about to be elected, Russia and Austria signed Löwenwolde's Treaty (on 19 August 1733) to support Frederick Augustus. Stanislas eventually had to leave Poland, and Frederick Augustus was elected as Augustus III of Poland.