By the mid-16th century, the Baltic region was at the center of a struggle between rising powers, driven by economic ambitions and shifting alliances. The decline of the Hanseatic League's monopoly over Baltic trade left Livonian cities like Riga, Narva, and Tallinn vulnerable, as they lacked adequate defenses and naval power to counter external threats. At the same time, Denmark, Sweden, and Russia pursued expansion into Livonia, each seeking greater control over trade routes and strategically valuable ports. For Russia, Livonia represented an opportunity to break out of isolation from the Baltic Sea, which hampered its ability to import advanced weaponry and engage with Western trade.
The Tsardom of Russia, under Ivan IV (Ivan the Terrible), sought to exploit the fragmented political landscape of the Livonian Confederation. With the annexation of Kazan and Astrakhan, Russia had grown stronger and now desired a corridor linking the Baltic to the Caspian Sea. However, when the Livonians failed to meet Russia’s demands for tribute, Ivan launched a military campaign in 1558, marking the beginning of the Livonian War. As Russian forces quickly captured key fortresses like Tartu and Narva, alarm spread among Livonia's neighbors, drawing in Poland-Lithuania, Sweden, and Denmark. These powers saw both a threat and an opportunity in Livonia’s collapse, and they began maneuvering to secure their own interests in the region.
Lithuania responded by aligning with Poland to form a mutual defense pact, which gradually drew both states deeper into the conflict. Although Poland-Lithuania achieved some military gains, the lack of cohesion between the two parts of the Commonwealth complicated war efforts. Lithuania’s involvement in the Livonian War also strained internal resources, exposing the limits of the new political framework. The transition from a personal union (where each state retained separate policies) to a fully integrated Commonwealth was still fragile, and disagreements between the Lithuanian and Polish nobility weakened efforts to resist Russian expansion effectively.
When Stephen Báthory ascended to the throne in 1576, he sought to revitalize the Commonwealth’s military efforts. As King of Poland and Grand Duke of Lithuania, Báthory launched a series of bold campaigns, including a joint Swedish-Lithuanian victory at Wenden reversing Russia’s advances. The Siege of Pskov (1581) and the recapture of Polotsk were critical victories that solidified the Commonwealth's hold over Livonia. The Truce of Jam Zapolski (1582) marked the end of Russia’s ambitions in the region, transferring former Russian holdings to Poland-Lithuania. This truce was a major strategic victory, securing trade routes and stabilizing the Commonwealth’s northern frontier.
Map showing the campaigns in Livonia and Western Russia of Stefan Batory during the Livonian War. The dark line is the approximate border by 1600. © Grandiose
However, the Livonian War also highlighted the vulnerabilities within the Commonwealth’s political system. Lithuania's success in the conflict depended heavily on cooperation with Polish magnates and nobles, further cementing the nobility’s influence over governance. This reliance on the szlachta (nobility) limited the monarch’s power and set a precedent for future internal conflicts. Though Báthory’s reign represented a brief resurgence in military strength, the Commonwealth's decentralized political structure would become a liability in later conflicts with Sweden and Russia, leading to the gradual decline of Lithuanian influence within the union.