Fortification
the art of increas- Fortifications ing, by engineering devices, the fighting power of troops who occupy a position.
The relation of fortification to the other great divisions of the art of warfare, of warfare , strategy and tactics, may be divided as follows: Strategy determines the location of the position, which must conform to the general plan of campaign; tactics determines the best disposition of the troops on the position, for offense or defense; fortification improves the natural features of the position so as to increase the chances of success . are commonly divided into two classes: "permanent fortifications" and "fieldworks." Under the former are included all works that are constructed for the defense of town, harbor, arsenal, dockyard, etc., being carefully laid out and built with a view to durability and the resistance of an attack, whenever it may be made; under the latter, all works are classed that are intended to serve a temporary purpose, such as siege-work and batteries for an attack on a fortress, or lines of intrenchment hastily thrown up for the protection of an army in the field, or to check the advance of an enemy on an important strategical position. These works differ mainly in the manner in which they are built, the ramparts and parapets of permanent works being faced or riveted with blocks of granite; the terre-plein of the rampart on which the guns are worked, the cheeks of the embrasures , casemates, bomb-proof buildings for magazines, etc. , being formed of the same material; while field-works consist of mounds of earth formed of that which is thrown FORTIFICATION up out of the ditch in front, having the ramparts and embrasures riveted with sods of turf, fascines, gabions, and sandbags, the terre-plein for the support of the guns and their carriages being made of pieces of thick timber strongly bolted together.
The great improvements lately made in the construction of heavy guns have rendered it necessary to revise the systems of fortification formerly in vogue. Iron and steel turrets are taking the place of masonry on low sites which are much exposed and where earth cannot be employed advantageously. These turrets are revolving cupolas, with spherical roofs; while in some instances the guns are mounted on disappearing carriages.
In the United States the frontiers exposed to attack being very largely maritime, the fortifications are principally batteries of heavy guns adapted to a contest with steel-plated ships. It was formerly usual to mount guns in masonry casements built tier over tier, but this method has been discarded in consequence of the modern developments in ships and guns. It was demonstrated during the World War when the Germans smashed the Belgian forts that earth and sand constitute the most effective defense. Stone, concrete and steel cannot withstand modern siege-guns.
Iron-clad Forts. Since 1859 the progress of fortification in Europe was in the direction of the use of some form of iron armor. In England the necessity for using iron in fortifications was apparent just as soon as this material began to be used in ships, and in 1861 England entered upon the work of rebuilding her forts with iron. It was substantially completed in 1878, at a cost of $37,000,000, expended on nine harbors. Within comparatively recent times have come the solid iron turrets, of enormous thickness, carrying two 80ton guns each, which form part of the defenses of Dover, England. While many of these forts, which were built while the contest between guns and armor was still in progress, can be pierced by the more recent guns, yet the number of large guns which they mount is far superior to the number that could be brought against them afloat, and in connection with torpedoes and ironclad ships they afford a secure defense. On the Continent the problem was not taken up till guns had reached a greater development, and then it was solved generally in the direction of using iron alone, in the form of turrets or domes. Some were of wrought iron, some of steel, and some of cast iron. The latter were the Gruson cupolas, of which many were constructed in various harbors of Ger- FORTRESS many, Austria, Belgium, Holland, and Italy. See FORT.