To understand the importance of Fortress Eben Emael, we must first go back to the start of the First World War. And the centrepiece of these modernization efforts was Fortress Eben Emael. If Eben Emael couldn’t be taken from the ground, Hitler thought, then how about from the air? Only minutes later, the 9 remaining gliders of Group Granite descended upon the grassy roof of Fort Eben Emael. Then, at noon on the 11th of May 1940, only 30 hours after the assault had begun, the garrison of Fortress Eben Emael finally surrendered.