Taft Board Seacoast Fortifications
Large direct firing guns were usually mounted singly, with traverses between them to protect them from enfilade by distant hostile fire and to limit the destructive effects of projectiles landing in adjacent emplacements. The distances between the guns vary with their size and with the nature of the ground. Where possible, in the case of the larger guns, it is rarely less than 100 feet. Mortars for indirect firing are mounted in pits. The first requirement for the mounting of a modern gun is a proper foundation from which the gun may be fired and which will permit it to traverse freely and accurately. While guns had increased remarkably in power, the weight of the gun proper had not increased in the same ratio. The usual precautions governing the design of foundations for heavy structures of course hold in the case of guns and mortars, in proportion to their weight.
The great increase in power of modern guns had, in addition, rendered corresponding precautions necessary to prevent the gun and carriage from being overturned by the recoil of the piece. Provision was made for offsetting the strain transmitted to the foundation by the weight and distribution of the material of the latter. In the case of some of the high-power English guns this resulted in the construction of practically solid concrete bases 25 feet in diameter and 10 feet deep. The traverse circle of the carriage is connected with this base by steel bolts two inches in diameter and extending nearly to the bottom of the base of concrete. A loading platform of suitable dimensions on which the men can work while loading the gun is provided in the rear of the gun.
As ordnance was loaded at the breech the service of the gun is considerably expedited, and the cannoneers are enabled to work in more safety under the cover of the parapet. The latter is a matter of considerable importance and is placed in front of the gun, connecting with the traverses on the side.
Where the gun was mounted on a disappearing carriage its muzzle projected over the parapet only in the firing position and recoils to a position in rear of the parapet for loading. If mounted on a barbette carriage, the gun stands permanently with its muzzle projecting above the parapet. The thickness which should be given the parapet was an open question among engineers. The rule laid down by some of the best authorities was that it should be 50 per cent thicker than the greatest penetration of any projectile liable to strike it. The modern method of constructing parapets is to make them of a mass of sand supported in rear by thick retaining walls of concrete immediately in front of the gun. Projectiles striking in the front slope of a thick mass of sand thus backed will usually be deflected upward and pass out through the superior slope of the parapet, doing little damage to it, as the sand drops back approximately into place. Lewis gives the thickness of the concrete retaining wall immediately in front of the gun for English emplacements for high-power guns at from 10 to 15 feet. The superior or upper slope, both of concrete and earth, have a slight slope to the front. The front slopes run off into the natural surface of the ground, and in this and other ways the concealment of the battery was secured in order to make it a difficult target for the enemy on the water.
The main magazine for a fort would consist of a building or buildings at suitable places convenient of access, in which powder in bulk, blank cartridges, shell, etc., may be stored. The service magazine at the gun emplacement should have a capacity for the ammunition immediately needed. At the time of the Civil War in the United States projectiles had not yet attained a weight too great to be handled by hand by two men. Now the largest of them weigh half a ton, and special appliances in the way of trolleys and wheeled trucks must be provided for handling them expeditiously. In view of the disastrous effects that may result from the explosion of a magazine, special precautions are taken to exclude hostile projectiles from it. This is accomplished by placing it in a relatively lower position than the gun and giving its walls an ample thickness of masonry and earth covering.
Moisture is injurious to powder, and many precautions are taken to exclude dampness from the magazines. In view of the fact that the service magazines are of necessity near the coast, and that the air around them frequently contains much moisture, the problem is a difficult one. Careful attention was given to drainage, so that the surface water may be carried off as rapidly as possible. Air spaces and French drains are provided to intercept water penetrating the mass of the cover. The masonry walls were made as tight as possible and waterproofed. By these means the infiltration of water is prevented. Condensation will, however, occur when damp air is admitted to the magazine and strikes the walls and material at a temperature below its dew point. The prevention of condensation is a problem of relative heat and cold, and is usually met by attempts at careful regulation of the ventilation, admitting air so far as possible only at times when it is the driest. The walls are also sometimes lined with brick, with a view to absorbing water which may be deposited on them if the magazines must be opened for a short time at unfavorable periods.
In a fortification there were many elements to be considered. Living rooms for the cannoneers are built in the emplacements. Provision must be made for lighting the emplacements, magazines, etc., in case of action at night. This was formerly done by means of lamps, but recently in the United States electric light and power have been furnished in seacoast batteries. Lookouts for the observation of gunfire must be built and the latest appliances for accurate fire control must be installed. Stairs and ramps are provided where necessary in the emplacement for free and easy communication between its various parts.
The project, as revised to 1916, called for a total of 1,301 guns and mortars, of calibers from 3-inch to 10-inch, inclusive. Of this number, 1,184, or 91 per cent, had been provided for, all of which, except 16, were mounted in fortifications. The basis of the ammunition allowance for continental United States is the provision of a sufficient quantity to carry through a twohour engagement one-half of the total number of guns mounted in the fortifications, two hours having been assumed as the maximum time during which any fortification is likely to be actively engaged by a fleet. Gunnery increased until by 1913 100 percent hits could be scored against moving targets with a 12-inch gun at 7-9,000 yards, and 50 percent hits on battleship-sized targets at ranges upto 15,000 yards, which was considered sufficient to deterany naval attack. The US Army led the world in the technology and tactics of coast artillery.
On December 8th, 1914, the British 12-inch cruisers Invincible and Inflexiblesank the German 8.3-inch cruisers Scharnhorst andGneisenau off the Falkland Islands. The engagement began at 16,500 yards. Then, on January 24th, 1915, the British 13.5-inch battle cruisers Lion and Tiger sank the German 8.3-inch cruiser Blücher and severely damaged the 11-inch cruiser Seydlitz at ranges between 17,000 and 20,000 yards. These extremely long-range engagements invalidated the American assumptions about the ranges of naval ordnance, and brought into question the adequacy of the nation's coastal defenses.
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