Camp (Lat. castra; the English name camp being from campus, 'a plain'). The arrangement of a ROMAN CAMP was according to a fixed and regular plan, and an army never halted for a single night without throwing up such an intrenchment capable of containing the whole of the troops and their baggage. Of course such a camp for the night was much slighter in construction than the castra stativa, or stationary camp, which was to shelter an army for some time. The most complete account of the Roman camp is furnished to us by Polybius, the companion in many campaigns of the younger Scipio. The camp, as described by Polybius, was intended to accommodate an ordinary consular army, consisting of two legions, each containing 4200 foot and 300 horse, together with the usual complement of socii, or allies—in all, 16,800 foot and 1800 horse. Its general form was square, each side 2017 Roman feet in length (the Roman foot being 11.65 English inches), the whole surrounded by a ditch (fossa), the earth dug out being thrown inwards, so as to form an embankment (agger), on the top of which was a palisade (vallum) of the wooden stakes (valli, sudes) which were carried by each soldier.
The whole camp was divided into two unequal divisions by a straight road, the principal thoroughfare of the camp, called the Via Principalis, 100 feet in breadth, running parallel with the front and rear of the camp. At each extremity of this road was a gate; these were respectively the Porta Principalis Dextra, and the Porta Principalis Sinistra.
In front of the enemy was the Porta Pratoria, and opposite it the Porta Decumana. These were the four outlets of the camp.
The upper portion of the camp, separated from the lower by the Via Principalis, contained about one-third of the space occupied by the lower portion. In its centre stood the Prætorium (1), or general's tent, in the middle of an open square extending 100 feet on each side of it, its sides each 200 feet long, extending parallel with the sides of the camp. To the left of the Prætorium was the Quæstorium (2), the quarters of the quæstor; to the right, the Forum (3), the public market of the camp. Immediately before the Prætorium ranged the tents of the twelve Tribuni and the Praefecti Sociorum, or generals who commanded the allies. In the spaces marked 4, 5, 6, and 7 on either side of the Prætorium, were the general's staff, including probably the Legati, together with the Pratoria Cohors, consisting chiefly of picked men selected from the Extraordinarii; the former two being cavalry, the latter two infantry. In 8 were the remainder of the Extraordinarii Equites, facing towards the Via Principalis; in 9 the remainder of the Extraordinarii Pedites, facing towards the agger or rampart. The spaces marked 10 were reserved for occasional auxiliaries.
The centre of the lower portion of the camp was occupied by the two Roman legions which constituted an ordinary consular army, consisting of the infantry and cavalry of both legionaries and allies. It was divided into two equal parts by the Via Quintana, a road, 50 feet wide, which ran parallel to the Via Principalis, while the whole of the interior was surrounded by an open space, 200 feet wide, between the rampart and the tents, which allowed the troops ample freedom for movement. The tents were pitched in the twelve oblong compartments sketched in the plan, six above and six below the Via Quintana, and separated from each other by roads 50 feet wide. Each of these compartments was 500 feet long, and was divided into ten rectangular spaces, the proportional size of which is exactly represented in the plan. In the spaces marked A, each containing 10,000 square feet, were the Equites of the Legion, each of the ten spaces being occupied by one turma of thirty men and horses. In B, each containing 5000 square feet, were the Triarii of the Legion, each of the ten spaces being occupied by a manipulus of sixty men. In C, each of 10,000 square feet, were the Principes of the Legion, each of the ten spaces being occupied by two manipuli of sixty men. The spaces marked D, each of 10,000 square feet, contained the Hastati of the Legion, each of the ten spaces occupied by two manipuli of sixty men. In E again, each containing 13,300 square feet, were the Equites Sociorum, each of the ten spaces occupied by forty men and horses; while in the spaces F, each 20,000 square feet in extent, were the Pedites Sociorum, each of the ten spaces accommodating 240 men.
The tents all faced the Viae which formed their boundaries. Before each gate was posted a strong body of velites, called custodes, to prevent a surprise of the enemy, while pickets of cavalry and infantry, called stationes, were thrown forward in advance in each of the four directions to give timely warning of the approach of an enemy. Finally, sentinels (excubæ) kept guard along the ramparts. The night, reckoned from sunset to sunrise, was divided into four equal spaces called vigiliæ. The watchword (signum) for each night was inscribed on small tablets of wood (tesseræ), which were passed along the whole lines, and returned to the tribunes again.
The different parts of the camp were so distinctly marked out and measured off beforehand, that the men on their arrival at once proceeded to their respective stations, as if they had entered a well-known city, and were marching to their accustomed quarters. After the Roman legions came to be divided into cohorts instead of maniples, the plan of the camp necessarily became somewhat altered, but its general plan and main features as to interior arrangement remained the same. In comparing the encampments of the Romans with those of his own countrymen, Polybius tells us that the Greeks trusted mainly to a judicious selection of their ground, and regarded the natural advantages which they thus secured as supplying in a great measure the place of artificial means of defence. The Greeks, consequently, had no regular form of camp, and no fixed places were assigned to the different divisions of the army. When the practice of drawing up the army according to cohorts, introduced by Marius and Cæsar, was adopted, the internal arrangements of the camp experienced a corresponding change. Latterly, even the square form was abandoned, and the camp was made to suit the nature of the ground. It was always held to be of importance, however, that the camp should occupy a defensible position, that it could not be overlooked, and that it had a command of water.
When stationary camps (castra stativa) came into more general use, we hear of several parts which are not mentioned by Polybius, for example, the infirmary (valetudinarium), the farriery (veterinarium), the forge (fabrica), &c.; and as a great variety of troops then came to be employed, they must, of course, have had new stations appointed to them in the camp. Standing camps were divided into castra æstiva, a permanent summer camp, and castra hiberna, a permanent winter camp. Many of the stationary camps ultimately grew into towns—an origin seen in the names of such English towns as Colchester, Winchester, Manchester, and Chester itself. Amongst the most perfect in Britain of those which retained the form of the simple encampment, is that at Ardoch (q.v.) in Perthshire, in the grass-covered mounds and ridges of which most of the divisions of the camp have been distinctly traced by antiquaries.
MODERN CAMPS.—The principles of castrametation, or camp-formation, underwent much change after the invention of gunpowder. Camps are now collections of tents or huts in which soldiers are lodged during a campaign or field manoeuvres. The immense size of European armies makes it impossible to carry tents for the troops, and they are almost always accommodated in Cantonments (q.v.) or Bivouacs (q.v.). The Italians alone retain the 'tente d'abri,' which, weighing only 11 lb., can be carried in portions by the three men who sleep in it. But in hot climates, and when, as in most British expeditions, the force engaged is comparatively small, they are placed 'under canvas,' forming what are called flying camps if occupied for one or two nights only, and standing camps if stationary for a longer period. At Aldershot (q.v.), Shorncliffe, Colchester, and the Curragh of Kildare, large camps of exercise have been established; and small instructional camps are formed for a few days every summer in the various military districts, to train the regulars, militia, and volunteers in the duties of camp life and field operations.
The full space required by a battalion of British infantry at war strength for a standing camp may be taken as 190 yards of front and 280 of depth; for one night 64 yards by 200 would suffice. In the centre of the front are the quarter-guard tents; then comes the parade ground, 80 yards deep; then the men's tents in 8 rows (1 per company), perpendicular to the front, each bell-tent taking 12 to 15 men, and each square Indian tent 22 to 25; in rear of the company tents are the field kitchens, then the officers' tents, then the baggage-wagons and horses, and last of all, the tents of the rear-guard.
The space required by a cavalry regiment is 186 yards of front and 255 of depth, or 68 by 180 for one night only. The tents are arranged in a manner similar to those of an infantry camp. The horses are fastened to picket ropes laid down between them.
Field artillery usually park their guns and wagons in front of their horse lines, and pitch the tents round the latter. The full space for one battery has a front of 100 yards and depth of 189—the minimum dimensions being 60 and 150 yards respectively.
Field-hospital, engineer, ordnance store, commissariat, and transport camps are similar to those for field artillery, and each unit requires about the same space as one battery. White flags with red Geneva cross by day, and a red lamp by night, indicate the tents of a field-hospital; a blue flag with white centre, or a green lamp, the commissariat and transport camp; and a blue flag with red centre, or yellow lamp, the ordnance store department. Twenty-five yards' interval is left between corps.
The site of a camp should have a plentiful supply of good water and wood for fuel, the ground firm turf, with sand or gravel subsoil, good natural drainage, easy communications throughout, and access to good roads in front and rear. Tactical considerations, if within two days' march of the enemy, are paramount, and must decide the position of the camp. Thus, a large force intending to fight a battle, in a chosen position, would be encamped or bivouacked in rear, but near enough to occupy it before the enemy's advanced artillery could come within range. Infantry would be encamped in front and on the flanks of cavalry and artillery, which take longer to turn out, and should therefore have this protection. The safety of such a camp would be insured by a strong line of outposts some three miles in front of the fighting position, and probably by an advanced cavalry screen 10 or 20 miles farther towards the enemy. It follows that the system of surrounding camps or bivouacs by defensive works is no longer necessary nor possible when armies of perhaps 250,000 men are in question. But if a small force is holding a point on the lines of communication or operating against savages, some obstacle is essential to check a sudden onslaught of overpowering numbers upon front, flank, and rear.
When, as on the march, time does not admit of regular fortification, some sort of protection must be improvised. This was done in the Soudan campaigns by utilising the baggage and by surrounding the camp with a 'zareba,' or impenetrable inclosure of thorn bushes cut down for that purpose. In Zululand also, the Boer method of forming a 'laager' round the camp by interlocking the baggage-wagons was adopted, after the disaster of Isandhlwana had demonstrated the necessity of some protection against the enveloping attack of the Zulu army.
The cantonments of a besieging army are strengthened against sorties by entrenchments, and entrenched camps have now superseded other forms of permanent Fortification (q.v.). Such a camp consists of a girdle of detached forts surrounding the enceinte at a distance of several miles, so that the area thus inclosed is a protected position from which a field army can operate. Paris, Portsmouth, and Metz are modern instances; the perimeter of the first being some 90 miles.