Roger de Vere

Died at the Battle of Damietta, The Fifth Crusade

Oxford had no legitimate issue by either of his wives, but left an illegitimate son, Roger de Vere, who died in 1221 at Damietta.12] Source:

http://en.wikipedia.org/wiki/Aubrey_de_Vere_IV

The Fifth Crusade 09, 1221 Crusaders are driven out of the city of Damietta by Malik Al-Kamil. July 1221 Crusaders under the command of Cardinal Pelagius set out for Cairo. August 30, 1221 Battle of al-Mansura: Crusaders under the command of Cardinal Pelagius, Papal Legate, are defeated in the Nile Delta and are forced to surrender. The Crusaders had been offered control of Jerusalem and other Christian sites in Palestine in exchange for the return of Damietta, but Cardinal Pelagius refuses and turns a potential victory into a stunning defeat that effectively ends the Fifth Crusade.