Duarte I of Portugal, also known as King Edward of Portugal, reigned from 1433 to 1438. He was the son of King John I of Portugal and Philippa of Lancaster. Duarte was known for his efforts to promote culture and literature during his reign, as well as for his attempts to strengthen the Portuguese monarchy. His reign was marked by challenges, including conflicts with the Castilian crown and internal disputes among the nobility. Duarte's untimely death in 1438 led to a succession crisis, ultimately resulting in the ascension of his son, Afonso V of Portugal.