Heiress of the duchy of Lancaster whose marriage to John of Gaunt in 1359 made him the richest nobleman in England; mother of Henry IV and of Philippa, queen of Portugal, and the lady mourned in Chaucer's Book of the Duchess.
Blanche of Lancaster was the younger daughter of Henry of Grosmont, Duke of Lancaster, Edward III's most celebrated captain, and the first wife of John of Gaunt, the king's third surviving son. When her elder sister died in 1362 she inherited the whole Lancaster estate, the largest private landholding in England, and her husband became Duke of Lancaster in her right.
Blanche was never a queen and died at about twenty-six, but her inheritance founded the royal House of Lancaster: her son became Henry IV of England in 1399, and her daughter Philippa married John I of Portugal and became the mother of the Portuguese princes of the House of Aviz. Geoffrey Chaucer's first major poem, The Book of the Duchess, is an elegy for her.
Blanche was born around 1342–1345, probably at Bolingbroke Castle in Lincolnshire, to Henry of Grosmont and Isabel de Beaumont. Her father was a crusader and diplomat and the author of a devotional book, the Livre de seyntz medicines, and Edward III made him the first Duke of Lancaster in 1351. On 19 May 1359, at Reading Abbey, Blanche married her cousin John of Gaunt under a papal dispensation, and the wedding was celebrated with jousts in London at which, it was said, the king and his sons fought disguised as the mayor and aldermen.
Almost everything said about Blanche's character comes from Geoffrey Chaucer, who served in her husband's circle. In The Book of the Duchess, written soon after her death, the grieving Black Knight describes his lady, called White, a play on Blanche, as fair, gentle, truthful and kind in speech. The poem is courtly praise written for a patron, and it shows how Gaunt's household wished her to be remembered rather than giving an independent portrait.
Froissart, who also knew the Lancastrian household, praised her as young and beautiful and recorded the lavish mourning for her. Beyond these tributes the record is one of property, children and devotion: she and Gaunt had at least seven children, three of whom survived, and her anniversaries were kept with great ceremony for decades.
Her father died of plague in 1361 and her elder sister, the wife of William of Bavaria, in 1362, leaving Blanche sole heiress. Edward III created John of Gaunt Duke of Lancaster in November 1362, and the Lancaster estates, with castles at Kenilworth, Leicester, Pontefract and Tutbury and the Savoy Palace in London, gave the couple an income second only to the crown's. Their surviving children were Philippa, born in 1360, Elizabeth, born in 1363, and Henry, born at Bolingbroke in 1367.
Blanche died on 12 September 1368, probably of plague. John of Gaunt kept her memory for the rest of his life, endowing chantries for her soul and commissioning a splendid tomb in St Paul's Cathedral from the mason Henry Yevele, where he was buried beside her in 1399. The tomb was destroyed in the Great Fire of 1666, and its appearance is known from Wenceslaus Hollar's engraving.
Blanche's inheritance made the dukes of Lancaster the one noble house wealthy enough to challenge the crown, and in 1399 her son used that power to depose Richard II and take the throne. Her grandchildren included Henry V of England and, through her daughter Philippa, the Portuguese princes of the House of Aviz, among them Henry the Navigator.