The Portuguese dynasty that secured independence at Aljubarrota and launched the Age of Discovery.
When Ferdinand I of the Afonsine line died in 1383 without a son, his daughter’s marriage to the king of Castile threatened to swallow Portugal. The Portuguese rallied instead around John, Master of the military Order of Aviz and illegitimate son of Pedro I, who was acclaimed king in 1385.
His crushing victory over the Castilians at the Battle of Aljubarrota in 1385, won with English longbowmen and the generalship of Nuno Álvares Pereira, secured both Portuguese independence and the new dynasty.
John I’s marriage to Philippa of Lancaster produced a remarkable set of princes whom the poet Camões called the "Illustrious Generation". In 1415 they seized Ceuta in North Africa, the opening move of Portuguese overseas expansion, and one of them, Prince Henry the Navigator, sponsored the voyages that pushed down the African coast.
The dynasty thus turned a small Atlantic kingdom into the pioneer of European maritime exploration, laying the foundations of a seaborne empire.
Edward’s short reign was overshadowed by the disastrous expedition to Tangier in 1437, in which his brother Ferdinand was left a hostage and died in captivity. His son Afonso V, called "the African", campaigned successfully at Arzila and Tangier but exhausted the kingdom pursuing a claim to the Castilian throne, checked at Toro in 1476.
These reigns balanced crusading ambition in Morocco against the slower, more profitable work of Atlantic exploration and trade.
John II, one of the ablest kings of the age, broke the power of the great nobles — executing the Duke of Braganza and personally stabbing the Duke of Viseu — and rebuilt royal authority. He drove the exploration effort that sent Bartolomeu Dias round the Cape of Good Hope in 1488 and negotiated the Treaty of Tordesillas dividing the wider world with Castile in 1494.
By the end of the medieval period the House of Aviz had made Portugal the leading power of oceanic discovery, poised for Vasco da Gama’s voyage to India in 1498.