Gilles was also Seigneur of Rochefort, Jodoigne and advocate of the abbey of Saint-Trond.
Gilles contracted leprosy, giving up most of his lands to his brothers Conon and Pierre.
[1][2] Gilles was succeeded as Count of Montaigu, Clermont and Duras by his brother Conon, possibly as early as 1175.
[3]) Leprosy, however, was not the end of his military life, according to Gislebert of Mons, as he and his brother Conon fought the duke of Louvain, for seizing Duras and Jodoigne, his only remaining allod.
Moreover, he writes of his capture in the town of Namur by Baldwin V, Count of Hainaut, who held him captive for a long time.