 Eleanor was born in about 1228.She was the youngest of four daughters and a co-heiress of the powerful Marcher lord William de Braose, and Eva Marshal, both of whom held considerable lordships and domains in the Welsh Marches and Ireland.Eva was one of the daughters of William Marshal, 1st Earl of Pembroke by Isabel de Clare, 4th Countess of Pembroke, daughter of Richard de Clare, 2nd Earl of Pembroke, "Strongbow".