THERE is no intention in the following pages to intrude within the province of the military engineer. No doubt it is a department of the art of war endowed with peculiar attractions to the scientific civilian. More than any other, both in its theory and its practice, it has been studied and worked out and taught in the closet. Men who never touched a weapon or saw the handling of troops, even in its simpler forms, come forth as oracles in attack and defence. A prophet recently arose among us, who told us that the whole of that vast science of flanking and covering, which has rendered the name of Vauban illustrious, is founded on an absolute fallacy, insomuch that the more elaborately it is wrought out, the more surely it leads to ultimate conquest, since every additional work stretching out from the centre is weaker than its predecessor, and in the end gives the enemy an approach towards it. In criticisms so audacious there is no present attempt to meddle. It is only intended to recall, by way of example and instruction, some instances of the dealing of historical fate with the fruit of human wisdom, when it takes the shape of a permanent fortification. This is obviously the department of the art of war that is most liable to be influenced by historical conditions, because it remains longer than any other in the hands of Time, and at the mercy of his fluctuations. The movable panoply of war shifts, like the costumes and decorations of the stage, with the shifting time and place of action. The weapons in the soldier's hands are of yesterday and to-day, but the rampart he fights behind may be a hundred, possibly six or even eight hundred, years old.

Scattered all over the world are countless remnants of ancient fortresses, become obsolete, and incapable either of protection or assault, from changes in the conditions surrounding them. They make a mark on the profile of the earth, or they give a touch of interest and picturesqueness to a morsel of natural scenerythat is all they are fit for now, though the days have been when they were the centre of all the excitement and tragic interest of war. They were designed by engineers of high repute and skill. They had their memorable annals of attack and defence, of which the faintest traditions have been forgotten for no one can say how many hundreds of years. What is now but a mass of shapeless stones and earthen mounds, may have been adored in tradition as the bulwark of a nation's independence, or bemoaned as the trophy of conquest; and to a like condition the triumphs of later military art are slowly moving onwards.

Of very ancient military works there is a sufficiency to present us with great variety, indicating a like restless shifting in the means of attack and defence. There are long ramparts to stop an army's march or the inroads of barbarians, such as the Wall of China, or the Roman Wall between Solway and Tyne. In thorough contrast to such remnants of skilled masonry are the rude hillforts, such as Caer Caradoc and the Caterthun,-astounding relics of labour, but revealing nothing except the general belief that from their remote mountain-position, and from their vast compass, they must have been not merely the protecting-works for garrisons of soldiers, but places of refuge for communities of people. The relics of another class of for

tresses, though more artificial and apparently less ancient, are still more reticent and tantalising in their revelations. They desert the natural strength of rocky mountainranges, and seek smaller eminences of sand or earth, artificially raised, or scarped out of natural elevations; and of these the obvious explanation is, that they were adapted for staking, and were occupied by works built of wood, like the abode of Cedric the Saxon. Fire was the great enemy and destroyer of such structures, and hence it is that in the tenth and eleventh centuries we hear of the burning down of fortresses as a frequent crisis in the tenor of a contest.

Come down into the periods of written European history, and we have a new and distinct object in the castle. We can trace it from its infancy in the simple block, down to the mighty maze, but not without a plan, of modern engineering; and its social changes and relations are equally distinct and emphatic. In fact, as we know the age of a tree by its rings, we can trace the history of the fortress by its outworks. Its origin belonged to the Norman race, and only where that race prevailed is it to be found in all the stages of its growth. It was not like the rampart of the Roman, guarding the marches of an empire; nor was it like the hill-fort, the place of refuge to which the community fled in time of danger. It was the dwelling-place of the new lord of the soil. As he was a hard and unpopular lord, it behoved that his house should be strong enough to protect him from violence. He administered justice-or the reverse -in his feudal court, and hence this house of his was also a place of punishment; and so, as it has been aptly said, the castle of the feudal baron was at once a mansion, a fortress, and a prison.

Of all the specimens, at whatever age they appeared, and on however great a scale, the primary feature is the simple square block, with scarcely a vestige of flanking-work, as we may see it in such noble specimens as Newcastle and the White Tower of London. As time and skill and wealth advance, so do flanking-works stretch out around. Thus we have the simple round towers at the corners, then the towered walls and protections of the bailey, as we see them at Carnarvon and Aberconway; and so on until we come to redoubts, bastions, glacis, ravelins, and all the complex evolutions of the Vauban system.

While all this transmutation goes on, there are other essential changes besides those of mere structure. It was a good policy, where it was practicable, to perch the strong square tower on a rock the most inaccessible to the enemy that was consistent with the convenience of its inhabitants. But when artillery made progress, height became less and less effective for war. It made the fortress difficult to take, but less worth taking, since it was not the artillery that pitched its metal from on high, but that which swept the surface of the earth, that was terrible to the enemy. An ingenious Artillery officer, indeed, wrote some years ago a pamphlet to show that a hollow might be preferable to a plain or an eminence as the site of a fortification. The parabola is the curve taken by a projectile; and were the hollow surrounded by elevations in the strict parabolic curve, each ball would take during its whole course the most desirable uniform distance from the earth, which is marked off at a few inches below the average stature of man. But nice calculations of this kind are apt to be thwarted by others equally precise and minute; and the parabola is