Fort Eben-Emael
From 1930 through 1939 the Albert Canal was constructed, cutting through parts of Mount Saint Peter. The first ships went through in 1940. The hill's strategic location made it the site of Fort Eben-Emael (1931–35), a major artillery defence point in the Belgian defences against any invading forces coming from Nazi Germany. At the opening of the war, the entire installation was taken quickly by a relatively small number of German paratroopers.