During the second period, however, Arnold of Rummen, the last indigenous claimant to the title of count of Loon, first had to sell the County of Chiny to the Duchy of Luxemburg to cover his military expenses, and soon after conceded defeat.

[2] Diederik of Heinsberg, the son of Louis' sister,[2] claimed the title of Count of Loon, and had himself proclaimed the heir with the assistance of John III, Duke of Brabant.

The chapter invoked a decision made at the Diet of Frankfurt of 13 August 1246, which stipulated that all ecclesiastical fiefs should return into the Catholic Church's possession if the vassal died without children.

The latter managed to rally the assistance of duke Wenceslaus of Brabant and Luxembourg (whom he was already serving as an advisor) and his half-brother, emperor Charles IV; moreover, his wife Elisabeth was rich.

That same year, John of Arkel invaded Loon anew; the ongoing war forced Arnold to sell Chiny to Wenceslaus, who merged it into the Duchy of Luxemburg.

In 1365, Arnold and Elisabeth's family fortress "De Warande" at Rummen (near Geetbets) was besieged for nine weeks from 9 August until 21 September by the prince-bishop, who conquered it and razed it to the ground.