The Lithuanian Civil War of 1389–1392 was the second civil conflict between Jogaila, King of Poland and Grand Duke of Lithuania, and his cousin Vytautas. At issue was control of the Grand Duchy of Lithuania, then the largest state in Europe. Jogaila had been crowned King of Poland in 1386; he installed his brother Skirgaila as ruler of Lithuania. Skirgaila proved unpopular and Vytautas attempted to depose him. When his first attempt to take the capital city of Vilnius failed, Vytautas forged an alliance with the Teutonic Knights, their common enemy – just as both cousins had done during the Lithuanian Civil War between 1381 and 1384. Vytautas and the Knights unsuccessfully besieged Vilnius in 1390. Over the next two years it became clear that neither side could achieve a quick victory, and Jogaila proposed a compromise: Vytautas would become Grand Duke and Jogaila would remain Superior Duke. This proposal was formalized in the Ostrów Agreement of 1392, and Vytautas turned against the Knights. He went on to reign as Grand Duke of Lithuania for 38 years, and the cousins remained at peace.
Background
The family of Gediminas ruled a state that covered the territories of present-day Lithuania, Belarus, Ukraine, Transnistria, and parts of Poland and Russia. Gediminas died in 1341; afterwards his sons Algirdas and Kęstutis, the fathers of Jogaila and Vytautas, co-ruled the Grand Duchy peacefully. However, after Algirdas' death in 1377, Kęstutis, Jogaila, and Vytautas began a power struggle. During their first conflict, the Lithuanian Civil War between 1381 and 1384, Vytautas and Jogaila both struck short-lived alliances with the Teutonic Knights. Vytautas did not manage to seize the throne and reconciled with Jogaila in 1384.
Jogaila created a significant new alliance with the Kingdom of Poland when he secured an agreement, known as the Union of Krewo (August 1385), to marry the twelve-year-old Queen of Poland Jadwiga of Poland. He married Jadwiga and was crowned jure uxoris king of Poland in February 1386. As a condition to the marriage and coronation, Jogaila agreed to renounce paganism himself and Christianize his subjects, and establish a personal union between Poland and Lithuania. The Union was an unwelcome development for the Teutonic Knights, as it united Poland and Lithuania, two states hostile to the Order, and a Christianized Lithuania deprived the Knights of their ideological justification for waging the Lithuanian Crusade. Thus the Order sought opportunities to undo the Polish–Lithuanian union; they demanded Samogitia, a section of western Lithuania that bordered the Baltic Sea, and refused to recognize Jogaila's baptism in 1386.
Vytautas became duke of Hrodna and Podlaskie; Jogaila known now by his Christian name Władysław II (Władysław II Jagiełło) designated his brother Skirgaila regent in Lithuania. Skirgaila, who also ruled Vytautas' patrimony in Trakai, was disliked by the Lithuanian nobility. Vytautas, on the other hand, became increasingly popular; Władysław II began to see him as a rival. Vytautas was supported by Lithuanians who resented the Polish interpretation of the recent Union of Krewo. These Lithuanians wished to maintain distinct legal structures and reserve official posts for Lithuanians. The Lithuanian elites also resented the changes in government that king Władysław II implemented there.
Civil war
1389–1390
Jogaila had sent Klemens Moskarzewski to establish a Polish garrison in Vilnius and stabilize the situation, but this move only angered the opposition. In May 1389 Jogaila tried to mediate the conflict between Skirgaila and Vytautas in Lublin. Vytautas was pressured into signing a formal document declaring that he was loyal to Skirgaila and supported him, but his position as Duke of Lutsk was not formally acknowledged. Vytautas secured his position in Lutsk, and turned his sights on Vilnius. According to Teutonic testimony at the Council of Constance, Vytautas planned to take advantage of his sister's wedding by sending wagons filled with meat, hay, and other goods to Vilnius. The wagons would be escorted by armed men, who would capture the castle once inside the city. This plan was uncovered by a German spy and the conspirators were executed. In another setback, two of Vytautas' strongest allies, his brother Tautvilas and his brother-in-law Ivan Olshanski, lost their territories in Navahrudak and Halshany.