1911 Encyclopædia Britannica, Volume 7… (1911)
“ DE LA WARR, or Delaware, an English barony, the holders of which are descended from Roger de la Warr of Isfield, Sussex, who was summoned to parliament as a baron in 1299 and the following years. He died about 1320; his great-grandson Roger, to whom the French king John surrendered at the battle of Poitiers, died in 1370; and the male line of the family became extinct on the death of Thomas, 5th baron, in 1426. The 5th baron’s half-sister Joan married Thomas West, 1st Lord West (d. 1405) , and in 1415 her second son Reginald (1394–1451) succeeded his brother Thomas as 3rd Lord West. ”
