Grand duke of Lithuania (1381-1382).
Kçstutis (Ger. Keistut, Pol. Kiejstut, Russ. Keistut) was born around 1300, a son of Grand Duke Gediminas. For several decades before becoming ruler of Lithuania, Kçstutis supported the power of his brother, Grand Duke Algirdas (1345-1377), and frequently led Lithuanian and allied armies against the Teutonic Order. Because Kçstutis had placed Algirdas on the throne of Lithuania, deposing their brother Jaunutis, he retained special influence. He ruled the important lands of Trakai, Podlachia, Brest-Litovsk, Hrodna (Grodno), and possibly Samogitia.
In the wars of the Baltic Crusades, Kçstutis became well- known to the Teutonic Order and its guest crusaders, and was even praised by them for his chivalrous qualities. Not only did he successfully fight off crusaders from all over Europe, but he also conducted negotiations for exchanges of prisoners and for possibilities of Lithuanian baptism. He nevertheless remained a pagan, yet learned many of the customs of the Christians. It is said that, when captured by the Teutonic Order, he escaped by riding away on the Grand Master’s horse, impersonating a knight of the order.
Algirdas’s son and successor, Jogaila, was not willing to defer to Kçstutis, and made a pact with the Teutonic Order against him. Kçstutis deposed Jogaila in 1381, seizing Vilnius and becoming grand duke. But Jogaila continued the struggle for power through new alliances with the Teutonic Order. He seized and imprisoned Kçstutis, and the old campaigner died in prison in 1382. He had been married to the Lithuanian noblewoman Birute, and one of his sons, Vytautas, became grand duke of Lithuania.