Treaty of Salynas Treaty of Salynas ( , ) was a peace treaty signed on 12 October 1398 by the Grand Duke of Lithuania Vytautas the Great and the Grand Master of the Teutonic Knights Konrad von Jungingen . It was signed on an islet of the Neman River , probably between Kulautuva and the mouth of the Nevėžis River . It was the third time , after the Treaty of Königsberg ( 1384 ) and Treaty of Lyck ( 1390 ) , that Vytautas promised Samogitia to the Knights . The territory was important to the Knights as it physically separated the Teutonic Knights in Prussia from its branch in Livonia . It was the first time that the Knights and Vytautas attempted to enforce the cession of Samogitia . However , it did not solve the territorial disputes over Samogitia and they dragged on till the Treaty of Melno in 1422 . The treaty . When Grand Duke of Lithuania Jogaila married Jadwiga of Poland and was crowned as King of Poland in 1386 , he appointed his unpopular brother Skirgaila as viceroy for Lithuania . Vytautas seized the opportunity to renew his struggle for power and started the Lithuanian Civil War ( 1389 – 1392 ) . He allied himself with the Teutonic Knights , promising them Samogitia . However , Jogaila and Vytautas reconciled in 1392 by signing the Treaty of Astrava . The Knights , betrayed by Vytautas , invaded Lithuania in 1394 and unsuccessfully besieged Vilnius for three weeks . The invaders were driven away by joint Lithuanian and Polish forces demonstrating that the old raids were no longer effective against the new Polish – Lithuanian alliance . A truce between the Knights and Vytautas was signed in 1396 . Vytautas needed to secure his western front as he was planning a massive campaign against the Golden Horde , which resulted in a disaster at the Battle of the Vorskla River in 1399 . Former Vytautas ' captive and friend Marquard von Salzbach helped to negotiate the agreement . A preliminary treaty was signed on 23 March 1398 , in Hrodna ; it was finalized in October 1398 . According to the treaty Samogitia was ceded to the Knights roughly up to the Nevėžis River , leaving the mouth of Nevėžis in Vytautas ' hands . For the first time the Order also received a portion of Sudovia , an almost uninhabited territory north and west of the Šešupė River . The treaty recognized spheres of influence : Veliky Novgorod for Vytautas and Pskov for the Knights . Vytautas also promised to help the Knights build two new castles as compensation for castles he burned in 1392 . The Knights promised to help Vytautas in his campaign against the Tatars . The treaty also guaranteed freedom of trade . Sigismund Kęstutaitis and other hostages kept by the Knights since the Civil War were released . During the week - long celebration following successful negotiations , Lithuanian nobles proclaimed Vytautas as King of Lithuania . While such a declaration had no political force , it was a reply to demands by Jadwiga of Poland to pay Polish taxes . It showed their determination to keep the Grand Duchy of Lithuania separate from the Kingdom of Poland despite the Union of Krewo in 1385 . Such a proclamation , known only from the chronicles of Johann von Posilge , raised doubts as to reliability among Polish historians . The treaty is noted among Lithuanian historians as it showed the extent of Vytautas ' power in Lithuania : he made territorial concessions without approval from Jogaila , who theoretically was the Supreme Duke of Lithuania . Aftermath . The Order attempted to take control of Samogitia . They took many hostages into Prussia and presented Samogitian nobles with gifts ( wool , salt , clothes ) . They also built fortresses – one with Vytautas ' help near Nevėžis River and another ( named Friedeburg ) near Dubysa . The Knights tried to maintain a friendly relationship with Vytautas , warmly welcoming his wife Anna during her piligrimage to the tomb of Dorothy of Montau and sent him gifts . However , soon disagreements arose when the Order demanded the return of about 4 , 000 peasants who escaped into Lithuania . Vytautas argued that they were free people and had the right to choose where to live . The disagreement grew into a war . The treaty was violated in March 1401 by Vytautas , who was assured Polish support by signing the Union of Vilnius and Radom in January 1401 . The Samogitians organized a local rebellion , capturing and burning the two newly built castles . In the fall of 1401 the Knights raided Kaunas and Hrodna ; in May 1402 the Samogitians burned Klaipėda . Vytautas joined the fight in 1402 by attacking Raudondvaris ( Gotteswerder ) . Jogaila ' s brother Švitrigaila joined the war on the side of the Teutonic Knights as he had laid claim to the throne of the Grand Duchy of Lithuania . He confirmed the Treaty of Salynas in exchange for Order ' s military assistance . When neither side could achieve decisive victory and Vytautas wished to concentrate his attention on troubles in Smolensk , the Treaty of Raciąż was signed on 22 May 1404 . It mirrored the Treaty of Salynas , but did not solve the disputes . The second Samogitian uprising in 1409 resulted in the Battle of Grunwald in 1410 .