While Portugal was subsumed under the Iberian Union, rebellious Portuguese factions and government in exile sought refuge and help in England.
England spearheaded the Anglo-Spanish War (1585–1604) on the side of the deposed Portuguese royal house.
In return Portugal compromised to transfer to the English the majority of the places recovered from the Dutch, to share in half the commerce of cinnamon and to install English families with the same privileges of the Portuguese families in Goa, Cochin, Diu, Bahia, Pernambuco and Rio de Janeiro.
Allegory of George III of the United Kingdom and John VI of Portugal, by Joaquim Carneiro da Silva (1810).
Her personal qualities were of the highest standard, and she reformed the court and imposed rigid standards of moral behaviour.
The English alliance was decisive in the consolidation of the independence of Portugal, and in Pedro's leadership.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.However, 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 Anglo-Portuguese Treaty of 1373 and confirmed at the Battle of Aljubarrota (1385) – with a pact of perpetual friendship between the two countries.