Weis' "Ancestral Roots. . ." (110:23). As Count of Poitiers, William II. "William IV of Aquitaine, Strong-Arm ('Fierebras', interestingly enough one of the sobriquets of the legendary William of Orange), did not share his father's [William Towhead] temperate ways. His over-indulgence in the chase and in women gave offense to his spirited wife Emma, the sister of the king, Hugh Capet. The upshot was two lengthy separations and ultimately his own taking refuge from the sins of the world in the religious life, leaving his young son in Emma's care."
--- D D R Owen, *Eleanor of Aquitaine, Queen and Legend*, Oxford (Blackwell) 1993, p 4-5.