Union of Krewo (1385): How Poland and Lithuania Joined Forces

The Union of Krewo was an agreement sealed at Krewo Castle in the Grand Duchy of Lithuania on 14 August 1385. In it Jogaila, the pagan grand duke of Europe’s last non-Christian state, promised to marry the young Queen Jadwiga of Poland, accept Catholic baptism and join his lands to the Polish crown. The short Latin charter began a partnership between Poland and Lithuania that lasted, in changing forms, until 1795.

Background: two states in need

In the 1380s the Grand Duchy of Lithuania was one of the largest states in Europe. Its rulers had expanded from the Baltic lands into Rus territories, so that most of their subjects were Orthodox Christians in what is now Belarus and Ukraine. The ruling dynasty and the Lithuanian heartland, however, remained pagan.

That made Lithuania the target of the Teutonic Knights, a crusading order based in Prussia and Livonia, who mounted almost yearly raids into the country. Earlier grand dukes had flirted with baptism, and Mindaugas had even been crowned as a Christian king in 1253, but each attempt was abandoned. Jogaila, who became grand duke in 1377, was also fighting his own relatives. His uncle Kestutis was seized and died in captivity at Krewo Castle in 1382, and Kestutis’s son Vytautas fled to the Knights and fought against Jogaila.

Poland faced a different problem. After the death of Louis I of Hungary in 1382, the Polish lords crowned his younger daughter Jadwiga in 1384, but she was a child and still needed a husband. The lords of Lesser Poland wanted a partner who could strengthen Poland against the Teutonic Order and recover lands it had lost. Jogaila, who was also weighing a marriage offer from Moscow, fitted that need.

The Moscow option would have meant Orthodox baptism and a turn towards the east, which many of Jogaila’s Orthodox subjects might have welcomed. A Catholic marriage, by contrast, offered a royal crown, a powerful ally against the Teutonic Order and a way to remove the Order’s justification for crusading against Lithuania. For the Polish lords, it promised to double the resources of the kingdom without a war.

The negotiations

Polish envoys and representatives of Jadwiga’s mother, Queen Elizabeth of Bosnia, travelled to Lithuania in 1385. Jogaila’s brother Skirgaila had already visited Krakow and Buda to press the proposal. The resulting document, dated 14 August 1385 at Krewo, is written as Jogaila’s set of promises to the envoys, made in return for the hand of Jadwiga and the Polish crown.

The text is short, only a few hundred words of Latin, and it reads more like a list of preliminary undertakings than a full treaty. The original parchment survives in Krakow. A small number of twentieth-century scholars questioned its authenticity, but most historians accept it, not least because every major promise in it was carried out in the following two years.

What Jogaila promised

The Act of Krewo contains a short list of commitments:

• To accept Catholic baptism together with his brothers, relatives and nobles, and to convert the pagan Lithuanians.
• To pay 200,000 florins to William of Austria, to whom Jadwiga had been betrothed as a child, as compensation for the broken engagement.
• To recover, at his own cost, lands that Poland had lost to its neighbours.
• To release Christian prisoners held in Lithuania.
• To attach his Lithuanian and Ruthenian lands “perpetually” to the Crown of the Kingdom of Poland.

The final promise used the Latin verb applicare. Polish historians long read it as a full incorporation of Lithuania into Poland; Lithuanian historians have generally seen a much looser dynastic tie. The word itself is ambiguous, and the debate reflects later national arguments as much as the medieval text.

What happened next

Jogaila kept his side of the bargain quickly. On 2 February 1386 Polish nobles at Lublin elected him king. He was baptised in Krakow on 15 February 1386, taking the Christian name Wladyslaw, married Jadwiga on 18 February and was crowned king of Poland on 4 March 1386 as Wladyslaw II Jagiello.

In 1387 he returned to Vilnius with Polish clergy, ordered the sacred fires and groves of the old religion destroyed, and oversaw mass baptisms of Lithuanians. A Catholic bishopric of Vilnius was founded the same year. Jogaila also granted privileges to Lithuanian nobles who accepted Catholic baptism, giving them rights over their estates similar to those of Polish nobles, a strong incentive to convert. Samogitia, in the north-west, remained pagan until about 1413-1417.

Key people

Jogaila (c. 1352/1362-1434), grand duke of Lithuania and, from 1386, king of Poland, founded the Jagiellonian dynasty, which later ruled Poland, Lithuania, Bohemia and Hungary.

Jadwiga of Poland (c. 1373/74-1399) was the crowned monarch whose marriage made the union possible. Her story is told in our article on Jadwiga of Poland.

Vytautas (c. 1350-1430), Jogaila’s cousin, reconciled with him and in 1392 became effective ruler of Lithuania under the Ostrow Agreement. His strong rule kept Lithuania largely self-governing.

Consequences

The union did not immediately create one state. Lithuania kept its own grand dukes and nobility, and relations were redefined several times: by the Union of Vilnius and Radom in 1401, the Union of Horodlo in 1413, and finally the Union of Lublin in 1569, which created the Polish-Lithuanian Commonwealth.

The arrangement also caused tension inside Lithuania. Many Lithuanian nobles resented rule from Krakow, and Vytautas fought a civil war against Jogaila’s representatives from 1389 until the Ostrow Agreement of 1392 made him grand duke in practice. The partnership worked best when the two cousins cooperated, as they did against the Teutonic Order.

The most immediate effect was military. Combined Polish and Lithuanian forces crushed the Teutonic Knights at the Battle of Grunwald in 1410, by which time Lithuania’s conversion had already undercut the Order’s claim that it was fighting pagans. Lithuania’s conversion also tied its elite more closely to Latin Christian culture, Polish language and Polish noble privileges over the following two centuries.

In modern times the union has been remembered differently on each side. In Poland it has often been celebrated as the start of a successful multinational state; in Lithuania it has sometimes been viewed as the beginning of a long process of Polish cultural dominance over the Lithuanian elite.

Myths and facts

• Myth: Krewo made Poland and Lithuania a single country in 1385. Fact: the countries remained separate states with a shared ruler for most of the next 184 years.
• Myth: Lithuania became Christian overnight. Fact: baptisms began in 1387, but Samogitia converted decades later and pre-Christian customs survived much longer in the countryside.
• Myth: the union was purely Polish conquest. Fact: Jogaila sought the deal to gain a crown, allies and protection from the Teutonic Order.

Timeline

• 1377: Jogaila becomes grand duke of Lithuania.
• 1382: Kestutis dies in captivity at Krewo; Louis I of Hungary and Poland dies.
• 1384, 16 October: Jadwiga is crowned in Krakow.
• 1385, 14 August: the Act of Krewo is issued.
• 1386, 15-18 February: Jogaila is baptised as Wladyslaw and marries Jadwiga in Krakow.
• 1386, 4 March: Jogaila is crowned king of Poland.
• 1387: the official Christianisation of Lithuania and founding of the Vilnius bishopric.
• 1569: the Union of Lublin creates the Polish-Lithuanian Commonwealth.

Why it matters

The Union of Krewo turned two rivals into partners, brought the last pagan state in Europe into Latin Christendom and created the Jagiellonian dynasty. Its effects shaped the borders, religions and cultures of Poland, Lithuania, Belarus and Ukraine for centuries.