Small military engagements produced mixed results for both sides, but the surrender of the main Russian force in February 1634 led to the Treaty of Polyanovka.

[6] Swedish king Gustav II Adolph sent envoys to Russia and the Ottoman Empire to propose an alliance and war against the Commonwealth.

[7] In May the Senate of Poland agreed to increase the size of the army, but Grand Lithuanian Hetman Lew Sapieha objected, arguing that the current forces were enough and that war was not likely.

[8] Russia, having recovered to a certain extent from the Time of Troubles, agreed with the assessment that the Commonwealth would be weakened by the death of its king, and unilaterally attacked without waiting for the Swedes and the Ottomans.

[11] The Russian army that crossed the Lithuanian border in early October 1632 had been carefully prepared and was under the experienced command of Mikhail Borisovich Shein, who had previously defended Smolensk against the Poles during the 1609–1611 siege.

[14] Dissatisfied with their traditional formations of musket-equipped infantry (the streltsy), the Russians looked to foreign officers to update the equipment and training of their troops based on the Western European model of regulars, dragoons, and reiters.

[16] Despite these difficulties, the city, commanded by Deputy Voivode Samuel Drucki-Sokoliński,[17] held out throughout 1633 while the Commonwealth, under its newly elected King Władysław IV, organised a relief force.

However, the process was delayed until the spring of 1633, when the Sejm officially sanctioned a declaration of war and authorised a large payment (6.5 million zlotys, the highest tax contribution during Władysław's entire reign) for the raising of a suitable force.

[17] Hetman Radziwiłł also managed to break through the Russian lines on several occasions, bringing about 1,000 soldiers and supplies into Smolensk to reinforce the fortress and raising the defenders' morale.

[6][12][15] By the summer of 1633, the relief force, led personally by the king and numbering about 25,000[6][13] (20,000 in the Polish–Lithuanian army, according to Jasienica), arrived near Smolensk; they reached Orsha on 17 August 1633.

[21] Only when Cossack reinforcements, led by Tymosz (Timofiy) Orendarenko and numbering between 10,000 and 20,000, arrived on 17 September would the Commonwealth army gain numerical superiority.

[12][21][22] The Cossacks under Orendarenko and Marcin Kazanowski raided the Russian rear lines, freeing the Polish–Lithuanian units under Radziwiłł and Gosiewski to join the effort to break the siege.

[9] In a series of fierce engagements, Commonwealth forces gradually overran the Russian field fortifications, and the siege reached its final stages by late September.

[12] As Stanisław Łubieński, the Bishop of Płock, wrote two weeks after Shein's surrender: "Our happiness is in remaining within our borders, guaranteeing health and well-being.

The treaty confirmed the pre-war status quo, with Russia paying a large war indemnity (20,000 rubles in gold), while Władysław agreed to surrender his claim to the Russian throne and return the royal insignia to Moscow.

[6][12][13] Jasienica notes that from the Russian perspective it was likely that Władysław's abnegation of his claim was more important, in terms of the subsequent increase in internal stability, than the loss of disputed borderland.

[10] Already during the later stages of the war, when the Commonwealth army moved from Smolensk to Bely, a new threat begun to loom on the southern borders, where the Ottoman Empire was massing an invasion force.

[14] A scapegoat was nevertheless needed: Mikhail Shein was accused of treason and, together with his second-in-command Artemy Izmaylov and the latter's son Vasily, executed in Moscow on April 28, 1634.

[40] After the war, Władysław gave the Russians the border town of Serpeysk and nearby territories, hoping to persuade the Tsar to join in an anti-Swedish alliance.