[5] Giles was probably responsible for the building of the tower of Brecon Cathedral[6] and is depicted in a window in the north aisle.
[1] In late 1206 John appointed a new sheriff of Herefordshire, who appears to have put pressure on both Braoses, father and son.
Giles aided Llywelyn ab Iorwerth's efforts to make an alliance with King Philip, which bore fruit in 1212.
The bishop, however, was concerned that the lands of his nephews, the sons of his elder brother William, were not returned to them, and in May 1214 efforts to find a compromise with the king failed.
This led Giles to join the barons opposing John, and in conjunction with the Welsh leader Llywelyn the Great, to raze Hugh de Mortimer's castle at Wigmore, Herefordshire.
After Llywelyn's revolt in May 1215, Giles and his brother Reginald de Braose seized their ancestral lands and the bishop himself took a number of the castles.