In 1007 he acquired secular authority in the county of the Cambrésis from the Emperor Henry II.
Erluin studied in the famous school of Liège, where he became archdeacon under Bishop Notker (972–1008), who procured his election to the bishopric of Cambrai.
Erluin appealed to the emperor, who invaded Flanders, captured Ghent and threatened to take the city's relics, but Baldwin remained in possession of Valenciennes.
[3] In 1011, Erluin refused a request by the dying castellan of Arras that his son, Walter II, be enfeoffed with his lands by the bishop in exchange for an oath of fealty.
The castellan failed to get his vassals and allies, including the count of Flanders, to fight before he died; Walter II swore the oath.