E. Cobham Brewer 18101897. Dictionary of Phrase and Fable. 1898.
An hypothetical castle in a forest near Saragossa. It represents that terrible obstacle which fear conjures up, but which vanishes into thin air as it is approached by a stout heart and clear conscience. The allegory forms the third part of the legend of Croquemitaine.
If a child disappeared, or any cattle were carried off, the trembling peasants said, The lord of Fear-fortress has taken them. If a fire broke out anywhere, it was the lord of Fear-fortress who must have lit it. The origin of all accidents, mishaps, and disasters was traced to the mysterious owner of this invisible castle.Croquemitaine, iii. 1.