It happened in the 20th century (90)

Dr Rafał Leśkiewicz

On 1 July 1569, the Union of Lublin, a landmark agreement that established a genuine union between the Kingdom of Poland and the Grand Duchy of Lithuania, was signed. While the union was effectively adopted on 28 June, it was on 1 July that the treaty was officially formalized through an exchange of documents, marking the dawn of the Polish-Lithuanian Commonwealth. Just three days later, on 4 July, this significant decision was ratified by King Sigismund II Augustus during the Sejm in Lublin.

The roots of Polish-Lithuanian relations trace back to the latter half of the 14th century, particularly with the Union of Krewo, which saw the marriage of Lithuanian Prince Władysław Jagiełło to Jadwiga of Poland, the de facto ruler of Poland. This union established a personal bond between the two nations, yet they remained distinct entities on the international stage, linked primarily through the Jagiellonian dynasty. The push for a more profound union was fuelled by strong support from a considerable faction of the Polish nobility, who recognized the necessity of solidifying their alliance, particularly in light of the looming uncertainty surrounding King Sigismund II’s potential death without an heir.

Additionally, the Grand Duchy of Lithuania faced a precarious position, especially in its ongoing conflict with Ivan IV the Terrible’s Russia over control of Livonia. In response to these pressures, extensive negotiations culminated in the convening of a Sejm at the end of 1568 in Lublin, where discussions began in earnest under the chairmanship of Stanisław Sędziwój Czarnkowski, while a parallel Lithuanian Sejm was also in session.

It is important to emphasize that not all Lithuanian magnates favoured the union. In a strategic move, Sigismund II Augustus presented a fait accompli by incorporating certain territories of the Grand Duchy, including the provinces of Volhynia, Kiev, Bracław, and the entire Podlasie region, into Poland. This decisive action, alongside territorial limitations imposed by Lithuania, ultimately paved the way for the realization of a real union.

In practical terms, this union introduced a joint Sejm and Senate, comprising 77 Polish deputies and 50 Lithuanian deputies in the Sejm, and 113 Polish senators alongside 27 Lithuanian senators in the Senate. It established a common monarchy, with the Polish king also serving as the Grand Duke of Lithuania, as well as a unified foreign and defence policy and a shared currency.

Despite these collaborative structures, both nations retained significant independence in various domains. They maintained separate armies and languages, and each country had its own treasury, legal system, and governmental institutions.

 Jan Matejko – Union of Lublin/ pl.wikipedia.org

The formation of the Polish-Lithuanian Commonwealth marked the emergence of the second-largest country in Europe, positioning it as a formidable political and military force on the continent. Today, the original document of the Union of Lublin is preserved and housed in the Central Archives of Historical Records in Warsaw.

Dr Rafał Leśkiewicz

Source: DlaPolonii.pl