Artillery. The tactical unit of field-artillery is the battery, composed in the United States of 6 guns, 9 caissons, 1 forge and battery-wagon, 1 store-wagon. The field-battery has 175 men and 150 horses, the horse-battery 165 men and 235 horses. The tendency in Europe is to reduce the battery to 4 guns, and with the adoption of a rapid-fire field piece (now undergoing trial) this will probably be the strength of the future field battery in the United States Army. A battalion (Abtheilung, group, brigade, division), composed of from 2 to 4 batteries, now constitutes an important organization on the battle-field. The tactical unit of coast artillery is also the battery, composed in this case, however, of a variable number of guns, usually from 1 to 4. The administrative unit of artillery in the principal armies of the world is the regiment, composed of from 2 to 5 battalions. It is the largest purely artillery organization. In the United States, since the recent reorganization of the artillery into a corps (see Artillery Corps), without regiments, the battalion is the administrative unit of the field-artillery, the district (the entire defense of harbor or post) of the coast artillery.
Mountain Artillery. The nations possessing mountainous regions generally have batteries of mountain artillery differing in organization and tactical use from the ordinary field-batteries. Thus, the Alpine batteries of France have a strength of 5 officers, 156 men, with 96 animals; those of Italy, of officers, 280 men, with 148 animals and 18 wagons; those of Switzerland of 7 officers, 162 men, and 83 animals.
Combined Arms. If we define the strategical unit as the smallest body composed permanently of two or more arms, and capable of acting independently, then the division of the European armies (the army corps of the United States Army) must be regarded as that unit. The smallest unit in which any two of the arms are combined is the cavalry brigade, which often has a horse-artillery battery attached to it, but this is only done to make it temporarily independent, and is not the rule. Ordinarily the brigade (cavalry or infantry) is the largest unmixed unit. The cavalry division is composed essentially of 2 brigades and 2 or 3 horse-batteries, although in the United States it has 3 brigades and a battalion of horse-artillery. The infantry division (the smallest unit in which the three arms are combined) consists in general of 2 infantry brigades, 1 cavalry regiment, 1 field-artillery regiment, and other special troops differing in the different countries. In France, however, there is no cavalry attached to the infantry division, and in the United States there are 3 brigades, 4 batteries, and no cavalry.
The highest definite unit of organization is the army corps, and its strength is determined by the fact that in its most unfavorable formation it must be capable of being assembled or any portion of itself in a single day. It is composed normally of 2 infantry divisions, 1 regiment of field-artillery, train and other services. In France, as there is no cavalry with the infantry divisions, a brigade of cavalry is attached to the army corps, and in the United States this unit is composed of three divisions, one or more regiments of cavalry, and the corps artillery. Since the artillery reserve was given up by Germany in 1899 the principal nations have followed this example, although a few still retain it. The total strength of an army corps is about 30,000 in all armies, forming a column about 15 miles long, its rear, therefore, one day's march from its head. Armies are simply aggregations of army corps and cavalry divisions, the artillery reserve being practically a thing of the past. The proportion of the three arms of the line is now considered to be best when the infantry and cavalry are in the ratio of 12 to 1, and there are 4 guns to every 1000 men of the other arms. The proportion of cavalry has been gradually made smaller since the days of Frederick, while that of the artillery has been gradually increased. In difficult mountainous country the cavalry is usually made less, but not if it can be used in raids at a distance. The proportion of artillery in flat, heavily wooded country, or in difficult mountainous country, or in country where the roads are bad, is usually decreased, because the full proportion cannot be used advantageously, and a smaller proportion would diminish the length of the column, which is always desirable.
Thus far only the line of the army, in its most restricted sense, has been considered, but the efficient working of an army also requires a number of special troops, such as the engineers, pioneers, railroad engineers, pontoniers, sappers and miners, signalers, telegraphers, balloonists, and the medical corps. In foreign armies all the special troops, excepting the medical corps, are designated by the general term technical troops. Of course, these do not all exist in any one army, and, although the corresponding classes in the different armies have similar duties, there is still considerable difference.
Engineers. The engineer troops of all armies are usually organized like infantry. In the German Army they comprise the pioneers and the railroad engineers the former organized into battalions of four companies each, the latter into regiments of two battalions each, including a balloon section. The latter is composed of six officers and about 150 men. The pioneers are charged with the construction of field fortifications and intrenched camps, bridge-building, the construction and destruction of communications and obstacles, and siege operations. The bridge train of a division has material for a bridge 38 yards long, and that of a corps 135 yards long, hence the entire bridge material of a corps and its divisions is sufficient for a bridge 211 yards long. The railroad engineers have charge of the construction of the narrow-gauge field railroad; each company can construct in one day about 7 miles of railroad complete, the track in working order ready for locomotives and cars. In the French army the engineer troops are organized into regiments, one of which is composed entirely of railroad engineers, the others being designated as sappers and miners; there is also a corps of telegraphers under the engineers. In the United States the engineers are organized into battalions of four companies each.
Signalers. The Signal Corps of the United States Army has charge of the field-telegraph, the military balloons, wireless telegraphy, and ordinary signaling by flag, torch, or heliograph (see Signaling and Telegraphing, Military). In the field an army corps will have attached to it one company of about 175 men, with material for at least 50 miles of telegraph-line. Military
