[1] William married Joan, daughter of Robert de Vere, 5th Earl of Oxford.
They had the following children: William was killed in a tournament at Croydon in 1286,[1] predeceasing his father.
It has been suggested that this was murder, planned in advance by William's enemies.
[2][3] On the 6th Earl's death the title went to John, the only son of William.
[4] John died without legitimate children, so on his death the title passed to Richard FitzAlan, 10th Earl of Arundel, eldest son of Edmund FitzAlan and John's sister Alice.