The Great Northern War (1700–1721) was a conflict in which a coalition led by the Tsardom of Russia successfully contested the supremacy of the Swedish Empire in Northern, Central and Eastern Europe. This period is seen by the contemporaries as a temporary eclipse, may have been the fatal blow that brought down the Polish political system. Stanisław Leszczyński was installed as king in 1704 under Swedish protection, but lasted only a few years. The Silent Sejm of 1717 marked the beginning of the Commonwealth's existence as a Russian protectorate: the Tsardom would guarantee the reform-impeding Golden Liberty of the nobility from that time on in order to cement the Commonwealth's weak central authority and a state of perpetual political impotence. In a resounding break with traditions of religious tolerance, Protestants were executed during the Tumult of Thorn in 1724. In 1732, Russia, Austria and Prussia, Poland's three increasingly powerful and scheming neighbors, entered into the secret Treaty of the Three Black Eagles with the intention of controlling the future royal succession in the Commonwealth.