Wikipedia
Lengvenis (Simeon Lingwen, born ca. 1360 – died after 1431; ; , ) was one of the sons of Algirdas, Grand Duke of Lithuania, and the ruler of Great Novgorod Republic (1389–1392, 1406–1411). He was known for his skills as a military leader.
Lengvenis was born to Algirdas and his second wife Uliana Alexandrovna of Tver. In 1387 battle with the Teutonic Knights Lengvenis commanded one of Lithuanian formations. In 1389–1392 he was appointed by his brother Jogaila, Grand Duke of Lithuania and King of Poland, as regent of Great Novgorod. He was baptized in the Orthodox rite as Simon and received the title of Prince of Great Novgorod. After Lengvenis lost this title in 1392, Vytautas the Great appointed him to Mstislavl. In 1406–1411 Lengvenis, once again, was nominated by Vytautas as regent of Great Novgorod. As ruler of Novgorod he led battles against Pskov, Livonian Order, and Sweden.
In 1410, Lengvenis participated in the Battle of Grunwald and commanded three banners from Smolensk. His son Yury commanded one of these banners. In 1411 Lengvenis participated in the signing of the Peace of Thorn. He was married to Maria Dmitrovna, princess of Moscow, the daughter of Dmitri Donskoi.
Lengvenis (Lengewin, Langwinus) was one of the local dukes in the early Grand Duchy of Lithuania during the reign of King Mindaugas (1230s–1263). First mentioned in 1242, Lengvenis was a nephew of Mindaugas (a son of his sister).
Around 1245, Lengvenis led Mindaugas' armies against Volhynia and was injured near Mielnik. Dukes of neighboring lands, three brothers Gineika, Milgerinas (Milgrynas) and Tučė (Dučius), grew unhappy with expanding power of Mindaugas and his clan. Just after the Volhynian campaign, they allied with the Livonian Order invaded Lengvenis' estate (believed to be in Nalšia, northeastern Lithuania with the center in Ginučiai Hillfort). Lengvenis and his family was captured and taken to Riga. Lengvenis' younger brother attempted to rescue them en route to Livonia, but was killed. After a ransom of 500 half groschen was paid, Lengvenis returned to his devastated estate. Lengvenis retaliated around 1247, when he successfully led a military campaign against the komtur of Cēsis. He defeated 500 men guarding the castle, killing the komtur and eight other knights.
He was mentioned for the last time in June 1260 as a witness to Mindaugas' act granting Lithuania to the Livonian Order in case he died without a legitimate heir. However, the act is considered to be a Livonian forgery.