The Union of Lublin: Agreement and Implementation

The Union of Lublin was a political settlement reached by the Kingdom of Poland and the Grand Duchy of Lithuania at the Lublin Sejm in 1569. Beyond their existing common monarch, it established institutions including a shared parliament. Military crisis, dynastic succession, and the rights of the nobility together drove its formation.

According to the introduction to Litwin's collection of documents, Muscovite forces' capture of Polotsk in 1563 increased pressure on Lithuania to seek military assistance. The childless Sigismund II Augustus wanted the two countries to remain connected after the dynasty ended. During the negotiations of 1569, Lithuanian representatives temporarily left Lublin. The king then incorporated Podlasie, Volhynia, Kyiv, and other regions into the Kingdom of Poland. The Lithuanian delegates returned in June to continue debating the boundaries between shared institutions and their country's rights.

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The act of union of July 1 was written in Polish. The Lithuanian text listed clergy, nobles, regional representatives, and representatives of the city of Vilnius, confirming their commitments through oaths and seals. Dubisz explains that the predominance of Lithuanian names does not mean Poland did not participate: this document took the form of Lithuania's estates reaffirming the union to Poland, with a corresponding instrument on the Polish side.

Agreement on union at the Sejm, confirmation by the monarch, and implementation of particular institutions were distinguishable stages. Małłek's legal history identifies royal confirmation instruments dated July 15, July 29, and August 11. The August 11 document also expressly ordered the union instruments to be entered in both chancelleries and authenticated sealed copies sent to the provinces, enabling local authorities to act on them.

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Article 3 described the Kingdom of Poland and the Grand Duchy of Lithuania as a shared political whole. Articles 4–7 provided for the nobles of both parts to elect one monarch, with the election held in Poland and coronation in Kraków. Lithuania would no longer hold a separate inauguration of its grand duke, though the title remained. Each new monarch had to confirm the rights, privileges, and liberties of both parts together.

Article 8 required a joint Sejm to deliberate on common affairs, with Lithuanian magnates and regional delegates entering its senatorial and representative structures respectively. Article 11 required mutual assistance and joint consultation on important diplomatic missions and foreign alliances. A new framework of common decision-making was established, but armies, treasuries, courts, and offices were not immediately merged into a single system; these retained their own organizations.

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Article 12 required common standards for coinage in weight, fineness, number, and inscriptions. This was an institutional objective to be pursued by the monarch, not proof that all mints and circulating coins had already been unified in 1569. Article 14 allowed people from either part to acquire landed property lawfully in the other, removing conflicting restrictions, while leaving acquired property subject to the law of its location.

The customs provisions in Article 13 also had a defined scope. Clergy, nobles, and their subjects could carry produce they had grown or raised free of the relevant land and water transit duties. Merchants' taxes remained payable, and using noble status to help merchants evade them was prohibited. The act thus facilitated cross-border movement for specified social groups and goods, rather than declaring all trade duty-free.

At the same time, Articles 9 and 15 preserved existing rights, courts, offices, and the name of the Grand Duchy of Lithuania. A common political whole and the continuation of local institutions were written into the same settlement.

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On July 19, the king separately regulated the authority of the Polish and Lithuanian court marshals. These officers maintained order where the monarch and Sejm were present, among other duties. The document required consultation and joint reception of foreign envoys. Court cases concerning people from one part were generally to be handled by that side, while cases crossing the two parts were to be heard jointly. It also assigned accommodation areas to Lithuanian magnates and deputies and left some questions of authority for the next Sejm.

The confirmation of August 11 further provided that the joint Sejm would normally meet in Warsaw, although serious circumstances could justify another location within Poland after consultation. Local assemblies of nobles in both parts would continue, receiving notice two to three weeks in advance. Lithuanian officers' places in the common Senate were also arranged under separately issued rules. Union therefore depended not only on a shared parliament but also on everyday coordination among local assemblies, chancelleries, and officials.

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Analyzing the document's language and structure, Dubisz argues that it served both legal and persuasive purposes. Its opening listed ranks and offices, the body explained the reasons for union and its institutions, and the conclusion reinforced permanence through promises and oaths. Its presentation of harmony and agreement must be read alongside the pressures and disagreements of negotiation.

Different linguistic forms in the signatories' names also reveal the complex cultural backgrounds of Lithuania's political elite. The name “Commonwealth of Two Nations” cannot simply be understood as a modern nation-state containing only two ethnic populations. The Union of Lublin created a community sharing a monarch and parliament within a noble political order while preserving numerous institutional differences.

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