The Army was nonetheless overruled by Hitler, who had a long-standing preference for huge, grandiose constructions. He preferred fixed installations along the lines of the virtually impregnable U-boat pens that had been built to protect Germany's U-boat fleet. In March 1943, he ordered the construction of a massive bunker (now known as the Blockhaus d'Éperlecques) in the Forest of Éperlecques near Watten, north of Saint-Omer. The bunker was soon spotted by Allied reconnaissance, and on 27 August 1943, a raid by 187 Boeing B-17 Flying Fortress bombers wrecked the construction site before it could be completed. A surviving portion was reused by the Germans as a LOX production facility.