In the early morning of 10 May 1940, the sky literally fell on the heads of the defenders of Fort Eben-Emael, considered to be Belgium’s most powerful fortress. This huge structure, with its powerful artillery and infantry weapons, was the key to the Meuse and Albert Canal defences. In the darkness of the pre-dawn, German DFS 230 gliders drifted silently over the southern Netherlands, landing one by one on top of Eben-Emael. Within minutes German Special Forces troops destroyed most of the fort’s weapons and observation capabilities. The following day, the garrison surrendered, and the door to Belgium and France was open. But, as Clayton Donnell relates in this perceptive and meticulously researched study, Eben-Emael was only one of the nineteen forts of the fortified positions of Liege and Namur attacked in May 1940. Three new and sixteen refurbished forts held out for several days, and fought to the death. The story he tells contradicts the common assumption that these static defences were rolled over or bypassed -powerless to resist the overwhelming force of the German combat engineer’s assaults, Stuka bombs and heavy artillery shells. In vivid detail he demonstrates that their importance in the 1940 campaign has been seriously under reported, and he gives clarity to some of the legends that have grown up around the capture of Eben-Emael itself.