The cadet branch of the Plantagenets that seized the English throne in 1399 and held it through the Hundred Years’ War and into the Wars of the Roses.
The house sprang from John of Gaunt, Duke of Lancaster, the third surviving son of Edward III and the richest magnate in England. Gaunt himself never ruled, but his vast Lancastrian inheritance and royal blood made his son a natural claimant when Richard II’s tyranny alienated the nobility.
In 1399 Gaunt’s son Henry Bolingbroke returned from exile, deposed Richard II, and took the crown as Henry IV — a usurpation that gave the dynasty its throne but also a permanent weakness of legitimacy.
Henry IV spent his reign defending his stolen crown against rebellion. His son Henry V turned outward, renewing the Hundred Years’ War and winning the overwhelming victory at the Battle of Agincourt in 1415. By the Treaty of Troyes in 1420 he was recognised as heir to the French throne and married Catherine of Valois.
Henry V’s early death in 1422 left the double inheritance of England and France to an infant, with his brother John, Duke of Bedford, ruling as regent in France.
Henry VI grew into a pious but weak king who suffered bouts of mental collapse, and under him the English position in France fell apart — helped on by Joan of Arc — until only Calais remained by 1453. At home, faction, debt, and the king’s incapacity discredited the regime.
From 1455 the rivalry between the Lancastrian court and the House of York erupted into the Wars of the Roses.
The dynastic wars swung back and forth: Henry VI was deposed by the Yorkist Edward IV in 1461, briefly restored in 1470, and finally destroyed in 1471, when his son Prince Edward was killed at Tewkesbury and Henry himself died in the Tower, ending the direct Lancastrian line.
The Lancastrian claim survived through the Beauforts, and in 1485 Henry Tudor — descended from John of Gaunt through that line — defeated Richard III to found the Tudor dynasty.
The House of Lancaster gave England the victories of Henry V and, in Henry VI, the collapse that opened the Wars of the Roses. The red rose of Lancaster became one of the most famous badges in English history.
Through the Beaufort line and the Tudor marriage of Lancaster and York, the dynasty’s blood flowed into the monarchy that followed the medieval age.