being entertained by
John I of Portugal. English aid to the
House of Aviz, which ruled Portugal from 1385 to 1580, set the stage for Portuguese cooperation with England that became a cornerstone of Portugal's foreign policy for more than five hundred years. English aid to Portugal went back much further to the 1147
Siege of Lisbon, when English and other northern European crusaders – en route to the Holy Land to participate in the
Second Crusade – stopped and helped Portuguese King
Afonso Henriques to conquer the city from the
Moors. In May 1386, the
Treaty of Windsor sealed the alliance – first started in 1294, renewed in the
Treaty of Tagilde in 1372 and the ensuing
Anglo-Portuguese Treaty of 1373 and confirmed at the
Battle of Aljubarrota (1385) – with a pact of perpetual friendship between the two countries. The most important part of the treaty stated that: In July 1386,
John of Gaunt,
Duke of Lancaster, son of the late king
Edward III of England and father of the future King
Henry IV of England, landed in
Galicia with an expeditionary force to press
his claim to the
Crown of Castile with Portuguese aid. He failed to win the support of the Castilian nobility and returned to England with a cash compensation from the rival claimant. John of Gaunt left behind his daughter,
Philippa of Lancaster, to marry King
John I of Portugal (February 1387) in order to seal the Anglo-Portuguese alliance. By this marriage, John I became the father of a generation of princes, called by the poet
Luís de Camões the "
Illustrious Generation", which led Portugal into its
golden age, during the period of the
Discoveries. Philippa brought to the
court the
Anglo-Norman tradition of an aristocratic upbringing and gave her children good educations. Her personal qualities were of the highest standard, and she reformed the court and imposed rigid standards of moral behaviour. On the other hand, the more tolerant Portuguese aristocracy saw her methods as too traditional or outdated. Philippa provided
royal patronage for English commercial interests that sought to meet the Portuguese desire for
cod and
cloth in return for
wine,
cork,
salt, and
oil shipped through the English warehouses at
Porto. Her eldest son,
Duarte, authored moral works and became
king in 1433.
Pedro, who travelled widely and had an interest in history, became
regent (1439–1448) after Duarte died of the
plague in 1438.
Ferdinand the Saint Prince (1402–1443), who became a
crusader, participated in the attack on
Tangiers in 1437. Henrique – also known as
Prince Henry the Navigator (1394–1460) – became the master of the
Order of Christ and the instigator and organiser of Portugal's early voyages of discovery. ==Disruption and renewal==