THE GRAND DUCHY OF LITHUANIA IN THE BEGINNING OF THE 15 TH CENTURY A er the death of Grand Duke Algirdas (1345–1377), his son Jogaila became the leader. In order to divert all a ention to the East, Jogaila signed a secret agreement with the Order, known as the Treaty of Dovydiškės, according to which the Order was free to a ack the lands belonging to Algirdas’ brother Kęstutis and his son, Vytautas. e Order informed Kęstutis of this agreement and in so doing initiated a civil war in Lithuania. At + rst, Kęstutis removed Jogaila from his seat of power, however, in 1382, Jogaila conquered Vilnius and imprisoned Kęstutis and Vytautas. Kęstutis was held prisoner in Krėva Castle, and was strangled by Jogaila’s servants. Vytautas managed to escape and sought protection with the Crusaders. Vytautas and Jogaila made peace in 1384, yet Jogaila once again failed to keep his promise to return Vytautas his fatherland, the Duchy of Trakai. In 1390–1392 Vytautas again appealed to the Order for assistance to go to war against Jogaila. Jogaila, who by now spent most of his time in Poland, could see that his appointed vicegerent, his brother Skirgaila, was unable to manage the internal opposition and so, once again made peace with Vytautas in 1392. at same year Vytautas became the actual leader of Lithuania, and o6 cially assumed this position in 1401. Wishing to reinforce Lithuania’s supremacy in the East – in the Ruzen and Tatars’ lands, Vytautas and the Order agreed on the Treaty of Salynas. According to this agreement, Vytautas relinquished Samogitia as far as Nevėžis and Kaunas as far as Rumšiškės to the Order. Undoubtedly, these Grand Duchy of Lithuania in the early 13-14th century. negotiations began with the aim of shaking o: Poland’s supremacy. e According to E. Gudavičius, V. Cukšynski defeat against the Tatars in the Ba le of the Vorskla River crushed all of Vytautas’ hopes of autonomy. By the beginning of the 15th century, when the dynastic and state integrity crises had ended, Vytautas’ aim was to establish Lithuania’s hegemony in the East, put an end to the Crusaders’ aggression, and secure complete juridical autonomy for Lithuania from Poland. In the + rst half of the 15th century the Grand Duchy of Lithuania was one of the largest states in Europe. Certi+ ed transcript of the Treaty of Dovydiškės. April 29, 1393. Secret State Archives Prussian Cultural Heritage Foundation, Berlin Ten year peace treaty of the Lithuanian Grand Dukes Jogaila, Kęstutis, Lengvenis and Vytautas with the Grand Master of the Teutonic Order, Winrich von Kniprode. Trakai. September, 29. 1379. Knight’s dagger. 14-15th century. Polish Army Museum in Warsaw Secret State Archives Prussian Cultural Heritage Foundation.