The fortress played a role in the defense of Liege in the First World War. On 5 August 1914 the Germans bombarded the eastern forts of Liege with infantry and artillery. The attackers were mown down, the shells of the artillery had no effect on the concrete walls of the forts. Yet the Germans managed i to invade the fortress through spaces between the forts. After fierce street fighting in Queue-du-Bois, on 7 August 1914 hills east of Chartreuse were conquered. The Germans found it as a empty village, the population had fled. The next morning, Chartreuse was occupied and the Germans invaded Liege by crossing the two bridges that were not destroyed.
During the First and Second World War, Fort de la Chartreuse was used as a prison by the Germans.
At the end of the Second World War Chartreuse was used as a military hospital for the Americans.
Until 1980the fortress was in use by the Belgian army.
Since 1980, the fort was abandoned and nature has taken over. The trees growing through the roof.