Brooks Adams,
The Law of Civilization and Decay…
(1896
| notes)
“ The Byzantine system was adopted. A double wall, the inner commanding the outer, with a moat between; and three enormous towers rising from the moat, formed the donjon. There were stone machicoulis and all the refinements of defence which appeared in France under Saint Louis and his son, and a study of this stupendous monument shows plainly whence Europeans drew their military instruction for a century to come. The Krak was the outwork dominating the plain where the Christians never made their footing good, and stood at the apex of a triangle of fortresses as remarkable as itself. ”
