ABSTRACT
With the concentric castle we have reached the final development of the military architecture of the Middle Ages. There was to be no further change of importance, till the introduction of gunpowder in the first half of the fourteenth century introduced an entirely new factor into the art of war, and began to turn in favour of the offensive the advantage which the defensive had hitherto enjoyed. In 1300 we leave the balance still inclined to the defender: the art of building strongholds had improved during the last two centuries far faster than that of destroying them. Siegecraft had made notable advances since the simple days of the first Crusade, but its developments always lagged behind those of military architecture. There was a limit to the mechanical application of the three powers of torsion, tension, and the counterpoise on which the engineer had to rely when constructing his siege-artillery. If he tried to gain increased force by enlarging the size of his machines, they not only grew too costly, but became hopelessly unwieldy and slow in their action. If, on the other hand, he tried to prevail by increasing their number, it was impossible, on account of their short range and great bulk, to concentrate the fire of a large quantity of them on a single piece of wall.
