Union of Lublin

In the summer of 1569, at a parliament held in Lublin, the Kingdom of Poland and the Grand Duchy of Lithuania bound themselves together as one state, the Polish–Lithuanian Commonwealth. The act, dated 1 July 1569, turned a loose dynastic link into a permanent union under a single elected monarch and a shared parliament. The resulting state was among the largest in Europe and lasted for more than two centuries.

Poland and Lithuania had shared rulers since the marriage of Jadwiga to the Lithuanian grand duke Jogaila, but they remained separate countries. By the 1560s that arrangement looked fragile. Sigismund II Augustus, king of Poland and grand duke of Lithuania, was the last of the Jagiellonian line and had no children despite three marriages, so the personal tie would end with him.

Lithuania was also under heavy military pressure. It had been losing ground in its wars with Muscovy and risked defeat in the Livonian War. Polish nobles were reluctant to keep paying for Lithuania's defence; in the 1560s as much as 70 per cent of the taxes raised in Poland went to that war. The Lithuanian magnates, for their part, feared that a closer union would place them on the same legal footing as the far more numerous Polish gentry and erode their power.

The Sejm met near Lublin in January 1569 but could not agree, and on 1 March most of the Lithuanian delegation, led by Mikołaj "the Red" Radziwiłł, walked out. Sigismund responded by transferring Podlachia, Volhynia, Bracław and Kiev from the Grand Duchy to the Polish Crown, a step widely welcomed by the local nobility, who saw advantages in joining Poland. These lands covered a large part of present-day Ukraine.

Weakened, the Lithuanians returned under Jan Hieronimowicz Chodkiewicz. They resisted Polish demands for outright incorporation and held out for a federal arrangement. The last objections were overcome on 28 June, the act was dated 1 July, and the king signed it at Lublin Castle on 4 July.

The two parts kept their own armies, treasuries, laws and administrations, but shared a monarch elected by the nobility of both, a common foreign policy and a single Sejm, which met in Warsaw. Because Poland was more populous, its deputies outnumbered Lithuanians about three to one. A common currency, the złoty, was introduced. Royal Prussia lost much of its autonomy, and Livonia became a joint possession of the two partners.

The union speeded the spread of Polish language and Catholicism among the Lithuanian and Ruthenian nobility, while peasants largely kept their own languages and faiths, widening the gap between lords and commoners. Polish settlement and the tightening of serfdom in the Ruthenian lands followed. Lithuania's own law code also endured: the Third Statute of Lithuania stayed in force in the former Grand Duchy, even after the partitions, until 1840.

Historians have judged the union both Sigismund's greatest success and his greatest failure. It created a vast state, but its weak monarchy and powerful magnates left it vulnerable, and it was destroyed by the partitions of 1772, 1793 and 1795. In the twentieth century, after the dispute over Vilnius, independent Lithuania formally renounced the union, while modern Poland regards the Commonwealth as part of its own heritage. The original document was added to UNESCO's Memory of the World Register in 2017.

Our 1530 map already draws Poland and Lithuania as a single block, although they were then still separate realms under one dynasty, and our 1600 map shows the united Commonwealth beside the Tsardom of Russia.