The chapel was built in 1946 in memory of the killed members of the resistance of the Secret Army, an armed Belgian resistance group. The symbol of this resistance group is an inverted triangle with a lion's head. The secret army was mainly active from 1944 after the Allies landed in Normandy. In September 1944, several resistance fighters gathered in this forest to attack the Germans with the Allies. The German troops became aware of the preparations due to treachery and attacked the animal shelter in Rotem (code name: Anatol), in which more than 130 resistance fighters from the region were killed or captured.