Eldest daughter of John of Gaunt whose marriage to John I of Portugal in 1387 sealed the Anglo-Portuguese alliance; queen for twenty-eight years, reformer of the court and mother of the Illustrious Generation, including Edward of Portugal and Henry the Navigator.
Philippa of Lancaster was the eldest child of John of Gaunt, Duke of Lancaster, and his first wife Blanche of Lancaster, and a granddaughter of Edward III of England. In February 1387, aged twenty-six, she married John I of Portugal, founder of the House of Aviz, sealing the alliance agreed in the Treaty of Windsor of 1386 and binding the new Portuguese dynasty to the English royal family.
She was queen of Portugal for twenty-eight years. Portuguese chroniclers praised her for reforming the morals and religious life of the court, and her children, among them Edward of Portugal, Peter, Duke of Coimbra, Henry the Navigator and Isabella, Duchess of Burgundy, became famous as the Illustrious Generation. She died of plague in July 1415, as her husband and sons were about to sail for the conquest of Ceuta.
Philippa was born on 31 March 1360, probably at Leicester Castle, though Bolingbroke Castle in Lincolnshire has also been proposed. Her mother died in 1368, and in 1371 her father married Constance of Castile, daughter and heiress of Peter of Castile, and claimed the Castilian crown in her right. Philippa and her sister Elizabeth were placed in the care of Katherine Swynford, who became their governess and her father's mistress, and whom he finally married in 1396. Her brother Henry, seven years younger, became Henry IV of England in 1399. In 1378 Philippa was admitted as a Lady of the Order of the Garter. Later writers claimed she was taught by Geoffrey Chaucer, Jean Froissart and John Wycliffe; all three moved in her father's circle, but there is no firm evidence that any of them taught her.
Most of what is said about Philippa's character comes from Portuguese chroniclers who served her sons. Fernão Lopes, keeper of the royal archives and chronicler to King Edward, portrays her as generous, devout and much loved, a queen who kept strict hours of prayer and arranged honourable marriages for the women of her household. Gomes Eanes de Zurara's chronicle of the capture of Ceuta, written for the same court, makes her deathbed a scene of exemplary piety and patriotism. Both men were celebrating the mother of their patrons, and their portrait is an idealised one.
Some evidence comes from outside the chronicles. Her surviving letters show her writing to the English court and interceding with her brother Henry IV of England for supporters of the deposed Richard II of England, and she helped persuade Thomas Fitzalan, Earl of Arundel, to marry her husband's illegitimate daughter Beatriz in 1405. She presented herself as a model of wifely modesty, reportedly saying that it would be unseemly for a wife to meddle in her husband's affairs, yet she was active in the politics of both kingdoms.
Philippa's marriage grew out of her father's ambitions in Castile. In 1385 John of Aviz, newly acclaimed king of Portugal, had defeated Castile at the Battle of Aljubarrota with the help of English archers, and on 9 May 1386 the Treaty of Windsor bound Portugal and England in perpetual alliance. That July John of Gaunt landed in Galicia to claim the Castilian throne, bringing his wife Constance and his daughters. When he met John I at Ponte do Mouro in November 1386, the two men agreed on a joint campaign and a marriage, and the king chose Philippa rather than Gaunt's younger daughter Catherine, who carried the Castilian claim.
John had been Master of the Order of Aviz, a military order bound to celibacy, and needed a papal dispensation to marry. The couple were married at Porto in February 1387, and the celebrations lasted fifteen days. The marriage was a matter of state. The king already had a mistress, Inês Pires, and two surviving children, Afonso and Beatriz, and Philippa allowed both to be raised at court while their mother entered a convent.
Philippa bore eight children between 1388 and 1402. The first two, Branca and Afonso, died young; the six who grew up were Edward, who succeeded as king in 1433, Peter, later Duke of Coimbra and regent, Henry, Duke of Viseu, Isabella, who married Philip the Good of Burgundy, John, Constable of Portugal, and Fernando, who died a captive in Fez after the failed attack on Tangier in 1437. The poet Luís de Camões later called them the ínclita geração, the illustrious generation.
Philippa kept close ties with England and brought English habits to the court, including, it is said, the Sarum rite of Salisbury for the royal chapel. Her household was noted for its discipline and piety, and her sons were educated to a standard unusual among Iberian princes: Edward wrote the Leal Conselheiro, a book of moral counsel, Peter travelled across Europe, and Henry the Navigator sponsored the voyages that opened Portugal's route down the African coast.
In 1415, as John I prepared a secret expedition against Ceuta in Morocco, plague broke out in Lisbon. Philippa withdrew with the court to Sacavém and then to the monastery of Odivelas, already weakened, according to later accounts, by fasting and vigils for the success of the enterprise. Zurara describes how, on her deathbed, she gave her three eldest sons, Edward, Peter and Henry, swords made for their knighting, each with a fragment of the True Cross, and charged them to keep their faith and the duties of their rank. She died on 19 July 1415. The fleet sailed a week later, and after Ceuta fell in August the princes were knighted there with her swords.
She was buried at Odivelas, and the following year her body was moved to the Dominican monastery of Santa Maria da Vitória at Batalha, which John I had founded to give thanks for Aljubarrota. After the king's death in 1433 the couple were laid together in a double tomb in the new Founder's Chapel, where their effigies lie hand in hand beneath the arms of Aviz and Lancaster and the insignia of the Garter, with the king's motto Por bem and the queen's Yl me plet carved on the tomb.