John of Portugal refers to several historical figures from the Portuguese royal family, most notably John I of Portugal, who reigned from 1385 to 1433. He was the founder of the Aviz dynasty and played a crucial role in establishing Portugal as a significant maritime power during the Age of Discoveries. His reign is marked by the victory at the Battle of Aljubarrota, which secured Portuguese independence from Castile. Another notable figure is John II of Portugal, who ruled from 1481 to 1495. He is known for his efforts to centralize royal power and for promoting exploration along the African coast. His reign set the stage for the later discoveries of Vasco da Gama and the establishment of a sea route to India.