On 21 January 1391 Vytautas' only daughter, Sophia of Lithuania, married Vasili I of Russia, Grand Duke of Moscow.
This alliance strengthened Vytautas' influence in Slavic lands and represented a potential new ally against Poland.
At the same time, Jogaila's brother Lengvenis was losing his power in Veliky Novgorod to Moscow.
The Teutonic Knights were idled during the protracted selection of their new Grand Master, Konrad von Wallenrode; their general chapter delayed his election.
In May 1391, the new master mortgaged Złotoria (Slatoria), a castle near Thorn, from Władysław Opolczyk, count palatine of Sigismund of Hungary, for 6,632 guldens.
This angered Jogaila and he invaded Dobrzyń Land, but was driven away.

Von Wallenrode called for new volunteers from France, England, and Scotland.
Among those who responded was William Douglas of Nithsdale.
During the autumn of 1391 the Teutonic Knights organized another campaign against Vilnius.
In Kaunas they organized a lavish feast, which was prominently featured in Konrad Wallenrod, an 1828 poem by Adam Mickiewicz.
They devastated the nearby towns of Ukmergė and Maišiagala, but lacked the resources for a second siege on Vilnius.
In November 1391 Vytautas attacked the areas near Merkinė and Hrodna, cutting off the easiest communication route between Jogaila and Skirgaila.

In the meantime the Knights were buying lands in Prussia.
In May 1392, von Wallenrode began negotiations with Sigismund of Hungary to buy Neumark for 500,000 guldens.
Negotiations fell apart as the title to the land was contested by several dukes.
The Neumark purchase was closed with Jobst of Moravia only in 1402.
During July 1392, the Knights agreed to pay Władysław Opolczyk 50,000 guldens for the Dobrzyń Land, which had been contested among Piast dukes since 1377.
Opolczyk, the ruler of Opole in Silesia, had little interest in the volatile regions to his north.
In 1392, he circulated a proposal to partition Poland among the Teutonic Knights, the Holy Roman Empire, Silesia, and Hungary, but it was rejected.
These purchases by the Knights threatened Poland's northern borders.

Neither Jogaila nor Vytautas had gained a clear advantage and the territories of the Grand Duchy affected by the civil war were being devastated.
Polish nobles were dissatisfied with the war; Jogaila was spending a great deal of time on Lithuanian matters and the expected benefits of the Union of Krewo had not materialized.
The Union was meant to strengthen Polish control over Galicia, Moldavia, and Wallachia rather than to create fresh troubles in the north.
Jogaila was preoccupied with the management of his court, battles in the southeast, and his sickly wife.
He attempted to replace Skirgaila with his younger brother Vygantas, but this brother died under unclear circumstances – according to rumor he was poisoned by either Vytautas or Skirgaila.
Klemens Moskarzewski was replaced with Jan Oleśnicki from Kraków as governor of Vilnius.
Jogaila decided to seek a compromise with Vytautas.
On 21 January 1391 Vytautas' only daughter, Sophia of Lithuania, married Vasili I of Russia, Grand Duke of Moscow. This alliance strengthened Vytautas' influence in Slavic lands and represented a potential new ally against Poland. At the same time, Jogaila's brother Lengvenis was losing his power in Veliky Novgorod to Moscow. The Teutonic Knights were idled during the protracted selection of their new Grand Master, Konrad von Wallenrode; their general chapter delayed his election. In May 1391, the new master mortgaged Złotoria (Slatoria), a castle near Thorn, from Władysław Opolczyk, count palatine of Sigismund of Hungary, for 6,632 guldens. This angered Jogaila and he invaded Dobrzyń Land, but was driven away.
Von Wallenrode called for new volunteers from France, England, and Scotland. Among those who responded was William Douglas of Nithsdale. During the autumn of 1391 the Teutonic Knights organized another campaign against Vilnius. In Kaunas they organized a lavish feast, which was prominently featured in Konrad Wallenrod, an 1828 poem by Adam Mickiewicz. They devastated the nearby towns of Ukmergė and Maišiagala, but lacked the resources for a second siege on Vilnius. In November 1391 Vytautas attacked the areas near Merkinė and Hrodna, cutting off the easiest communication route between Jogaila and Skirgaila.
In the meantime the Knights were buying lands in Prussia. In May 1392, von Wallenrode began negotiations with Sigismund of Hungary to buy Neumark for 500,000 guldens. Negotiations fell apart as the title to the land was contested by several dukes. The Neumark purchase was closed with Jobst of Moravia only in 1402. During July 1392, the Knights agreed to pay Władysław Opolczyk 50,000 guldens for the Dobrzyń Land, which had been contested among Piast dukes since 1377. Opolczyk, the ruler of Opole in Silesia, had little interest in the volatile regions to his north. In 1392, he circulated a proposal to partition Poland among the Teutonic Knights, the Holy Roman Empire, Silesia, and Hungary, but it was rejected. These purchases by the Knights threatened Poland's northern borders.
Neither Jogaila nor Vytautas had gained a clear advantage and the territories of the Grand Duchy affected by the civil war were being devastated. Polish nobles were dissatisfied with the war; Jogaila was spending a great deal of time on Lithuanian matters and the expected benefits of the Union of Krewo had not materialized. The Union was meant to strengthen Polish control over Galicia, Moldavia, and Wallachia rather than to create fresh troubles in the north. Jogaila was preoccupied with the management of his court, battles in the southeast, and his sickly wife. He attempted to replace Skirgaila with his younger brother Vygantas, but this brother died under unclear circumstances – according to rumor he was poisoned by either Vytautas or Skirgaila. Klemens Moskarzewski was replaced with Jan Oleśnicki from Kraków as governor of Vilnius. Jogaila decided to seek a compromise with Vytautas.
Lithuanian Civil War (1389–1392)