Jogaila

Family

Jogaila was designated by his father to be his heir (replacing his older half-brother Fiodor in that role) and ascended the Lithuanian throne after Algirdas's death in 1377. Depending on which year he was born with, he was either around 14 or 24 years old at the time of becoming the Grand Duke. The former possibility is supported by the fact during Jogaila's early reign his mother Uliana of Tver acted as regent; additionally, Vytautas the Great in his Memorial noted that his father Kęstutis (Algirdas's brother) ruled over Lithuania "until he [Jogaila] grew up and people get used to him", which suggests Jogaila would have been very young and presumably underaged – therefore in his teens rather than 20s – when he had come to the throne.