Union of Krewo
In a strict sense, the Union of Krewo or Act of Krėva (also Union of Krevo, Act of Kreva) was a set of prenuptial promises made in the Kreva Castle on 14 August 1385 by Jogaila, Grand Duke of Lithuania, in exchange for marriage to the underage reigning Queen Jadwiga of Poland. The act was very limited in scope and in the historiography the term "Union of Krewo" often refers not only to the particular document but to the events of 1385–1386 as a whole. After the negotiations in 1385, Jogaila converted to Christianity, married Jadwiga, and was crowned King of Poland in 1386. The union was a decisive moment in the histories of Poland and Lithuania; it marked a beginning of the four centuries of shared history between the two nations. By 1569 the Polish–Lithuanian union grew into a new state, the Polish–Lithuanian Commonwealth, and lasted until the Third Partition in 1795.
 Situation in Poland
Louis I of Hungary died on September 13, 1382. Since he had only two surviving daughters, Mary (born ca. 1371) and Jadwiga (born ca. 1373), Poland faced a succession crisis. Candidates for the throne included Mary's fiancé Sigismund of Luxembourg, Siemowit IV, Duke of Masovia, and Władysław Opolczyk. Mary and her fiancé were rejected by the Polish nobles, who did not wish to continue a personal union with the Kingdom of Hungary. Polish nobles competed with each other and a brief civil war broke out in Greater Poland. Eventually, after long negotiations with Jadwiga's mother Elizabeth of Bosnia, who was regent of Hungary, Jadwiga arrived in Kraków and was crowned as King of Poland (not as Queen of Poland, to emphasize her rights to the throne) on October 15, 1384. The new monarch still needed a suitable husband. She was betrothed to William of Austria, who in summer 1385 traveled to Poland in an attempt to consummate the proposed marriage and present a fait accompli. He succeeded in reaching Wawel, but was forcibly removed by Polish nobles. It is unclear whether he succeeded in consummating the marriage, but biased Austrian sources continued to accuse Jadwiga of bigamy. Nobles from Lesser Poland, including Spytek of Melsztyn, Jan of Tarnów, Jan Tęczyński, proposed the Jadwiga married Jogaila, Grand Duke of Lithuania.
 Situation in Lithuania
Grand Duke Algirdas died in 1377 and left the throne to his son Jogaila. He inherited a large state, inhabited by pagan Lithuanians and Orthodox Ruthenians. For the last century, Lithuanians defended themselves from the Teutonic Knights, a crusading military order dedicated to conversion of the Grand Duchy into Catholicism. Jogaila understood that the conversion was inevitable and searched for the best opportunities. The Treaty of Dubysa of 1382 with the Knights included provisions of Jogaila's conversion within four years. However, the treaty was never ratified. Accepting Christianity from a long-standing enemy was dangerous, unpopular, and could push Lithuania into dependence of the Knights. In 1384, Jogaila explored another option, presented by the Grand Duchy of Moscow and brokered by his Orthodox mother Uliana of Tver: converting to Orthodoxy and marrying Sophia, daughter of Dmitry Donskoy. However, in the eyes of Catholics, Orthodoxy was not any better than paganism. Therefore such conversion would not protect from the Teutonic attacks. A third option, presented by Polish nobles, avoided major pitfalls of the Teutonic or Muscovite proposals.
 Union of Krewo
The relations between Poland and Lithuania were not particularly friendly. The two states were allies before, when Jogaila's aunt Aldona of Lithuania was Queen of Poland between 1325 and 1339. Poland and Lithuania battled each other in the decades-long Galicia–Volhynia Wars, but also saw opportunities to regain lands lost to Hungary and regarded the Teutonic Knights as the common enemy. It is unknown who and when proposed Jogaila as the groom for Jadwiga. Some hints show that planning and negotiations might have started as early as 1383. For example, Jogaila attacked Siemowit IV, Duke of Masovia, when he advanced his claims for the Polish throne. By the time Lithuanian envoys participated in Jadwyga's coronation in fall 1384, Jogaila's candidacy was widely known.
In mid-1385, Jogaila sent an official delegation to Poland. It included his brother Skirgaila, Duke Boris (possibly his cousin and son of Karijotas), and merchant Hanul. Hanul helped Jogaila to recapture Vilnius during the Lithuanian Civil War (1381–1384) and represented interests of merchants, who saw great trade potential between Poland and Lithuania. The representatives first appeared before the Polish nobles in Krakow and then before Queen Elizabeth, Jadwiga's mother, in Buda. A Polish delegation – two Elizabeth's envoys and three Polish nobles – was sent to Lithuania. Upon return of the Lithuanian delegation, Jogaila confirmed in writing all the promises, made on his behalf in Poland. This confirmation in known today as the Union of Krewo.
The 560-word document is addressed to Queen Elizabeth and the Polish delegation. Jogaila briefly described the mission of the Lithuanian delegation and, in exchange for marriage to Jadwiga, agreed to the following:
- Christianizing Lithuania: conversion of pagan Jogaila, Lithuanian nobles and all pagan Lithuanians to Roman Catholicism
- paying compensation of 200,000 florins to William, Duke of Austria for the termination of the engagement between Jadwiga and William
- returning of all lands lost in wars by Poland. This in particular referred to territories in Red Ruthenia that Louis I of Hungary attached to the Kingdom of Hungary.
- releasing of all Christian war prisoners held by the Lithuanians
- attaching (Latin: applicare) of Lithuanian and Ruthenian lands to the Crown of Poland
It was guaranteed by the seals of Jogaila's brothers Skirgaila, Kaributas, Lengvenis and their cousin Vytautas. Because the document contained promises and guarantees only by one party, Lithuanian historian Jūratė Kiaupienė concluded that the union could not have been a final international treaty and that there should have been another document finalizing the agreement.
 Marriage and conversion of Lithuania
On January 11, 1386, a Polish delegation met Jogaila in Vawkavysk and presented him with a pre-election pact, declaring that the Polish nobility agreed to elect him as their new king. The election was concluded on February 1 in Lublin. On February 12, Jogaila and his relatives arrived in Kraków and were baptized by Bodzanta, Bishop of Gniezno, three days later in the Wawel Cathedral. Jogaila's new baptismal name Wladislaus was chosen in honor of Jadwiga's great-grandfather king Władysław I the Elbow-high, the penultimate Piast. Jogaila married Jadwiga on February 18 and was crowned jure uxoris as King of Poland on March 4. Due to negative propaganda by William of Austria and the Teutonic Knights, the marriage was not confirmed by Pope Urban VI (1378–1389); only Pope Boniface IX (1389–1404) declared it legitimate.
Right after the marriage and coronation, Jadwiga and Vytautas marched to Galicia where they defeated Hungarian forces and secured some 97,000 square kilometres (37,000 sq mi) in western Podolia. Andrei of Polotsk, Jogaila's eldest brother, used his absence to renew struggle for the throne of Lithuania. Andrei attacked southeast of Polotsk, the Livonian Order attacked Duchy of Lithuania, and Sviatoslav of Smolensk attacked Mstsislaw. The rebellion was quickly subdued.
At the end of 1386, Jogaila returned to Vilnius to carry out his other promise – to convert the Grand Duchy to Catholicism. He brought some priests, established the first seven parishes, and, according to Jan Długosz, even personally translated Lord's Prayer and Apostles' Creed into the Lithuanian language. New converts were baptized en masse, with little teaching, and were awarded wool shirts; the haste was later criticized at the Council of Constance. On February 17, 1387, Jogaila decreed that he would build Vilnius Cathedral and petition the pope to establish the Diocese of Vilnius, which he awarded with land possessions in Tauragnai, Labanoras, Molėtai. Two other privileges, issues on February 20 and March 4, 1387, awarded nobles who would convert to Christianity with new rights and granted Magdeburg rights to Vilnius. This served not only as an incentive for conversion but also equalized nobility rights in Poland and Lithuania.
 Polish–Lithuanian union
Jogaila left his brother Skirgaila as his regent in Lithuania. He proved to be unpopular and Lithuanian nobility resented growing Polish influence in the state. Vytautas seized the opportunity to renew his struggle for power and the Lithuanian Civil War (1389–1392) broke out. This was resolved with the Ostrów Agreement – Vytautas became the Grand Duke of Lithuania while Jogaila retained rights of an overlord. Vytautas conducted independent internal and foreign affairs, but cooperated with Jogaila. A celebrated example of the Polish–Lithuanian cooperation was the decisive victory in the Battle of Grunwald (1410) against the Teutonic Knights. Polish–Lithuanian relations were and Vytautas's independence were formalized by the Union of Vilnius and Radom (1401) and Union of Horodło (1413). Thus the Grand Duchy of Lithuania retained its sovereignty. Only the Union of Lublin (1569) created permanent union between Kingdom of Poland and Grand Duchy of Lithuania, after which the federal state Polish–Lithuanian Commonwealth was established. Finally, the Constitution of 3 May 1791 declared that both states were one, albeit this was denounced in 20 October amendments (Reciprocal Guarantee of Two Nations). Soon, they were separated in form, but most of the 19th century they spent under Russia, although administratively separate. In the early 20th century, both established their independence and since then, they have not been together in any formal sense.
Up until the discovery of the original document in 1835 in a register in the Archives of the Cracow Cathedral Chapter, the Union of Krewo was unknown. Usually important state documents were archived at the Crown Archive. It was neither referenced in any contemporary documents nor cited by medieval historians, no chronicles or other written sources mentioned the August 1385 meeting in Kreva. This led the Lithuanian American lawyer Jonas Dainauskas to question act's authenticity in 1975. However, his claims gained little scholarly support.
The word applicare, describing future relationship between Poland and Lithuania, caused most controversy and academic debate. The Latin term does not a have a legal definition and possibly was deliberately was chosen for its vagueness. The term is subject to wide-ranging interpretations, which could be divided into three major categories:
- Lithuania ceased to exist as a sovereign state and became a province of Poland. This interpretation was championed by Polish historians Feliks Koneczny (1862–1949), Anatol Lewicki (1841–1899), Henryk Łowmiański (1898–1984), and Ludwik Kolankowski (1882–1956). This view was newly interpreted by Oskar Halecki (1891–1973), who argued that Lithuania was incorporated into Poland from 1386 to 1401, then became Poland's fief to 1440.
- Lithuania became a fief of Poland. This view was introduced by Jan Adamus (1896–1962) in 1932 and supported by Henryk Paszkiewicz (1897–1979) and to an extent by Oskar Halecki. Their main arguments was that in reality such a large state could not suddenly became a province and that the Grand Duchy preserved most of the elements of sovereignty.
- Lithuania and Poland were united by a personal union. This view was introduced by Lithuanian historians Adolfas Šapoka (1906–1961) and Zenonas Ivinskis (1908–1971). They argued that Poland and Lithuania were united only by the monarch.
- Kiaupienė 2002
- Davies 2005, p. 94
- Ivinskis 1978, p. 284
- Kiaupa 2000, p. 127
- Ivinskis 1978, p. 280
- Ivinskis 1978, p. 281
- Ivinskis 1978, pp. 282–283
- Ivinskis 1978, p. 282
- Ivinskis 1978, p. 283
- Jučas 2000, p. 114
- Ivinskis 1978, p. 286
- Davies 2005, p. 95
- Jučas 2000, p. 116
- Jučas 2000, p. 115
- Ivinskis 1978, p. 288
- Jučas 2000, pp. 126–127
- Jučas 2000, p. 120
- Jučas 2000, p. 122
- Jučas 2000, p. 110
- Jučas 2000, pp. 111–114
- Davies, Norman (2005), God's Playground. A History of Poland. The Origins to 1795 I (Revised ed.), Oxford University Press, ISBN 978-0-19-925339-5
- Ivinskis, Zenonas (1978), Lietuvos istorija iki Vytauto Didžiojo mirties, Rome: Lietuvių katalikų mokslo akademija, LCC 79346776 (Lithuanian)
- Jučas, Mečislovas (2000), Lietuvos ir Lenkijos unija, Aidai, ISBN 9986-590-95-7 (Lithuanian)
- Kiaupa, Zigmantas; Jūratė Kiaupienė, Albinas Kunevičius (2000), The History of Lithuania Before 1795, Vilnius: Lithuanian Institute of History, ISBN 9986-810-13-2
- Kiaupienė, Jūratė (2002), "Summary", 1385 m. rugpjūčio 14 d. Krėvos aktas, Vilnius: Žara, ISBN 9986-34-080-2
- Subtelny, Orest (1988), Ukraine: A History, Toronto: University of Toronto Press, ISBN 0-8020-5808-6
- Works related to full-text of Union of Krewo at Wikisource (Latin)