On November 3, 1656, an intermediary armistice was signed between the State of Moscow and the Polish-Lithuanian Commonwealth. The armistice placed the Moscow Tsar on the Polish throne, a move necessitated by the need to unite against a common enemy, Sweden, which proclaimed war in 1656.
The event took place in the course of the 1654-1567 Russian-Polish war for control of the Ukrainian and Belorussian territories. The conflict was triggered by Orthodox riots in the Polish-Lithuanian Commonwealth, which was under pressure from the Catholic Poles. Once the situation aggravated, Bohdan Khmelnitsky, the Ukrainian hetman – the head of the Cossack army – requested aid from the Moscow Tsardom, in return pledging allegiance to the Moscow Tsar.
The Moscow Tsardom entered the war in 1654. Very successful in the beginning, the united Cossack and Russian armies were able to liberate the entire Western part of the Moscow Tsardom and win back several important territories, seriously weakening the Commonwealth.
The King of Sweden took advantage of the Commonwealth’s weak position and attacked Poland, occupying a significant part of its territory. The depleted Poland sought a truce with the Moscow Tsardom, and the two countries agreed to unite their forces against their common enemy. This decision was sealed by the armistice signed at the city of Vilno, now Vilnius, on November 3, 1656.
During the negotiations, the Russians had stronger positions, having conquered much of the Commonwealth’s territory in the first campaign, so they demanded that they would only call a truce, and they demanded that the Moscow Tsar, Aleksey Mikhailovich or his heirs, occupied the Polish throne. In return, the Tsar promised to give the newly acquired lands back to the Commonwealth. The Polish authorities agreed, but as the armistice could only come into effect after approval by the Lithuanian Parliament, they kept putting the sessions off.
The treaty was never approved; instead, it produced a stir inside the Cossack forces loyal to Moscow, who strongly disapproved Moscow bonding with Poland. To make things worse, the Cossack loyalty to Moscow was jeopardized after the death of the pro-Russian hetman Khmelnitsky. Ivan Vyhodsky, his successor, turned part of the Cossack Army away from Russia and toward the Commonwealth. He annulled his allegiance to Moscow and signed a separate treaty of cooperation with the Commonwealth, which undermined the Russian-Polish armistice and ruined Moscow’s plans to establish cooperation with the Commonwealth.
The hostilities between the Moscow Tsardom and the Commonwealth continued for several more years with varying success, but was reduced to local actions until all forces were depleted. The war was put to an end by signing of the Andrusovo Peace Treaty in 1667. Poland ceded to Russia the fortress of Smolensk and the left-bank of Ukraine, thereby ending its existence as one of Europe’s largest states.