Warsaw Confederation, 1704.
It was formed on 16 February 1704 in Warsaw, by the opponents of king Augustus II rule, as the Commonwealth faced the advance of the Swedish army. Amid its leader one can list: primate Michał Radziejowski, voivode of Poznań Michał Leszczyński, marshal of the Greater Poland Confederation Piotr Bronisz and Hieronim Lubomirski. The confederates, considering themselves as the authorities of the Commonwealth, engaged themselves in peace and alliance talks with Sweden. Under the pressure of the Swedish general Arvid Horn, the interregnum was declared, what ultimately led to calling the election sejm, during which, on 12 June 1704, Stanisław Leszczyński was proclaimed king.
See: K. Jarochowski, Dzieje panowania Augusta II od wstąpienia Karola XII na ziemię polską aż do elekcyi Stanisława Leszczyńskiego (1702-1704) [The history of king’s Augustus II rule, since Charles XII invasion of Polish territory to election of Stanisław Leszczyński], Poznań 1874.