Cecilia of Lancaster was born in 1360 and was a member of the English royal family. She was the daughter of John of Gaunt, the Duke of Lancaster, and Blanche of Lancaster. Cecilia's lineage connected her to the English throne, as her father was a prominent figure in the Plantagenet dynasty. In 1371, Cecilia married Robert de Vere, the 9th Earl of Oxford, which further solidified her family's influence. The couple had several children, and Cecilia's descendants played significant roles in English history. She passed away in 1416, leaving a legacy tied to the nobility of her time.