Source: Frederick Lewis Weis, Magna Charta Sureties, 4th Edition, (1968),28-2.
GILBERT de CLARE, son of Surety Richard de Clare, and himself a Surety,was born about the year 1180. In June 1202 he was entrusted with thelands of Harfleur and Mostrevilliers. He was one of the Barons stillopposing the arbitrary proceedings of the Crown.
He championed Louis the Dauphin, fighting at Lincoln under the Baronialbanner, and was taken prisoner by William Marshall, whose daughter helater married. He led an army against the Welsh in 1228 and capturedMorgan Gam, who was released the next year.
After an engagement in Brittany, he died on his return at Penros in thatDuchy, 25 October 1230. His body was conveyed by way of Plymouth andCranbourn to Tewkesbury. He was buried there before the High Altar 10November 1230.
He married Isabella, sister of William Marshall, the Surety, and daughterof William Marshall, the Protector, on 9 October 1217. She died 17January 1239/40