The Belgian command was counting on Eben-Emael to be the key defense of the northern frontier at Liège. It naturally attracted the first German attacks. Its enormous dimensions dictated an unconventional attack strategy, using airborne troops. The fort was attacked on 10 May 1940 and rendered ineffective in a few hours by a team of 75 men armed with new shaped-charge explosives. Ineffective Belgian defense of the fort's surface allowed the German assault team to use their explosive charges to destroy or render the fort's gun turrets and machine gun cloches uninhabitable.