Diederik of Heinsberg, Count of Loon

An agreement of 1190 stipulated that if the House of Loon were extinguished, the county would then be integrated with the Principality of Liège.

The Prince-Bishop of Liège, Adolph of La Marck moved to incorporate the County of Loon into the principality, while Diederik maneuvered to assume the title of count.

However, since Diederik had married Adolph's sister and the bishop was fond of their son, family relations won out.

But the death of the bishop did not terminate possession the Counties of Loon and Chiny by the Heinsbergs, because Adolph's nephew Engelbert III succeeded him as Prince-Bishop of Liège.

Engelbert removed the threat of excommunication pronounced against Diederik and allowed him to remain at the head of the counties until his death.