Following the death of Sigismund III Vasa in 1632, Władysław IV Vasa ascended to the throne, inheriting the challenges of maintaining stability in the sprawling Polish–Lithuanian Commonwealth. His reign began with the Smolensk War (1632–1634) against Russia, a conflict initiated by Tsar Michael I to exploit the temporary power vacuum in the Commonwealth. Russian forces invaded Lithuania, laying siege to Smolensk. Władysław personally led the Commonwealth’s army, broke the siege, and surrounded the Russian troops under Mikhail Shein, forcing their surrender in 1634. The Treaty of Polyanovka ended the war, with Russia agreeing to minor concessions, paying indemnities, and Władysław relinquishing his symbolic claim to the Russian throne.
After securing the eastern front, Władysław turned his attention southward, dealing with the threat from the Ottoman Empire. In 1633, Ottoman forces tested the Commonwealth’s defenses, but Hetman Stanisław Koniecpolski led a successful campaign that renewed peace between the two powers. The treaty reaffirmed the Commonwealth’s independence, alleviating the threat of Tatar raids and confirming the Commonwealth’s influence over the region.
Meanwhile, Władysław faced challenges in the north with the expiration of the Truce of Altmark between the Commonwealth and Sweden. While the king hoped for military gains to reclaim lost territories and assert his dynastic claim to the Swedish crown, the Sejm favored diplomacy. The Treaty of Stuhmsdorf (1635) ensured the return of key territories in Prussia but left most of Livonia under Swedish control, weakening Władysław’s ambitions.
Throughout his reign, Władysław attempted to reform the Commonwealth's political and military structures. His efforts included modernizing the army, establishing a navy, and negotiating increased royal authority. However, many of his proposals, such as creating a chivalric order and raising trade tariffs, faced staunch opposition from the szlachta (nobility). This resistance highlighted the entrenched power of the nobility and the limitations of royal authority within the Commonwealth's decentralized political system.
Although Władysław navigated his reign without major internal revolts, tensions simmered beneath the surface. His inability to enact substantial reforms and the growing dysfunction of the legislative system left the Commonwealth unprepared for future challenges. His death in 1648 marked the end of relative stability.