Blanche of Lancaster

Blanche of Lancaster was a member of the English royal House of Plantagenet, daughter of the kingdoms wealthiest and most powerful peer, Henry of Grosmont, 1st Duke of Lancaster. She was the first wife of John of Gaunt, the mother of King Henry IV, and the grandmother of King Henry V of England.

She was the younger daughter of Henry of Grosmont, 1st Duke of Lancaster and his wife Isabel de Beaumont. She and her elder sister Maud, Countess of Leicester, were born at Bolingbroke Castle in Lindsey. Maud married Ralph de Stafford and then William I, Duke of Bavaria however, Maud did not have children so her younger sister inherited their fathers titles and estates.

Source: Wikipedia