July 1, 1569

Union of Lublin

Polish and Lithuanian estates conclude the Union of Lublin

The union was embodied in two matching documents exchanged across the aisle — one carrying 140 seals, the other 77.

1 July 1569, at the joint Sejm in Lublin

At the joint Sejm in Lublin, representatives of the Kingdom of Poland and the Grand Duchy of Lithuania executed and exchanged two corresponding union documents dated 1 July 1569.

The Polish-side document carries 140 seals; the Lithuanian-side document 77.

Sigismund II Augustus's royal confirmation is dated 4 July, which is why both dates sometimes appear.

One monarch, one Sejm — and two of everything else

The act joined the Crown and the Grand Duchy under one commonly elected monarch and a common Sejm and Senate, replacing the looser personal union with a constitutional "real union."

It established joint foreign policy and currency while Lithuania retained separate ministers, treasury, laws, courts, administration and army.

Historians variously call the result a federation, a confederation, or an intermediate early-modern arrangement; treating any one modern label as definitive is misleading.

The transfers happened before the union

Most Lithuanian delegates, led by Mikołaj Radziwiłł "the Red," had left Lublin on 1 March in opposition to incorporation.

Sigismund answered by transferring Podlasie, Volhynia, Bracław and Kyiv to the Polish Crown during the March–June negotiation crisis. Those acts were imposed by the king; they were not produced by provincial votes on 1 July.

Returned Lithuanian representatives, with Jan Hieronimowicz Chodkiewicz among the negotiators, then accepted a closer union that still preserved the Grand Duchy's state institutions.

Sources

Researched 24 Aug 2026 6 sources not yet audited

How this was checked

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What the sources leave uncertain

The reciprocal estate documents are dated 1 July; Sigismund's royal confirmation is dated 4 July, producing occasional references to both dates.
Historians variously call the Commonwealth a federation, confederation, or an intermediate early-modern arrangement. Treating any one modern label as definitive is misleading.
Ruthenian nobles' attitudes toward incorporation varied; recent scholarship rejects older accounts that reduce them to either passive victims or unanimous enthusiasts.