TRANSPORT OF ARTILLERY At the present time the draught horse is in process of being replaced by mechanical transport for all heavier types of artillery. This change is necessarily a gradual one, and its nature and prog ress in different countries are partly determined by the extent to which the mechanical transport which has replaced the horse in civil life can be rendered available for military purposes.
Artillery may be mechanized in several ways. The self-pro pelled gun-carriage has the gun-mounting built into it, and is preferably of the "caterpillar" type. The artillery tractor pulls the gun behind it, and carries the detachment and first supply of ammunition. The artillery carrier or transporter carries the gun on a platform from which it is dismounted, by a ramp, for firing. From the tactical point of view, the self-propelled gun-carriage is not yet satisfactory, as it is too vulnerable and too large for con cealment, and requires an undue amount of labour to entrench. The motor is useless while the gun is in action, when, if it were separable from the gun, it would be most useful in bringing up ammunition. Against these defects, however, may be put the asset of its power to move forward instantly if blinded by a hostile smoke cloud. Further it is better suited than other forms of artil lery for the support of a rapidly moving force of armoured fighting vehicles.
The artillery tractor may be a cater pillar or a vehicle of the lorry type. Both forms are open to the objection that the complicated mechanism of a Q.-F. gun is dam aged by rapid travelling on the road, even if the wheels be pro vided with rubber tyres. This, however, can be obviated by the use of low 2-wheeled travelling platforms, as employed in the Italian artillery for road travel. The caterpillar tractor is good across country, but on roads inherently less rapid and less econom ical, for its power, than the wheeled vehicle. Various attempts have been made to construct tractors and carriers having both road wheels and caterpillar tracks. The American Christy tractor, now no longer in use, travelled normally on road wheels, and had a caterpillar band which was put on round the wheels for cross country work. The French St. Chamond carrier-tractor is a com plete caterpillar vehicle, with an extra pair of road wheels on extensions of the chassis at each end, which can be raised well clear of the ground, allowing the vehicle to rest on the caterpillar tracks.
Another vehicle, of a different type, is the "4-wheel-drive" lorry, in which the wheels are driven independently. This is excel lent on the road, and is capable of moving over easy country. The Pavesi agricultural tractor is a small 4-wheeled vehicle with a flexible connection between the fore and hind carriages, which enables it to adjust itself to irregularities of the surface of the ground. Its four wheels are driven independently and have remov able "spuds" which are put on for cross-country work. It has a i6h.p. engine burning paraffin or petrol. The road speed is about five miles an hour, and the machine is therefore unsuited for the rapid transport of reserve field artillery.
The artillery carrier saves the gun from road strains, but entails delay in lowering the gun on to the ground when it comes into action, and in hoisting it up again with a ramp and winch. Many tractors, such as those of the American caterpillar type, can be fitted with platforms and used as carriers. It is not practically possible to fire the gun from the carrier, as this would entail a considerable increase of weight and complication. Any commercial lorry or truck of sufficient capacity can be adapted to carry light artillery. Its movement, however, is generally restricted to hard surfaced roads. As regards the difficulty of combining a road vehicle, and a cross-country vehicle, the carrier is subject to the same disadvantages as the tractor. Experiments are now being carried out in a number of countries with six-wheeled motor vehicles which may be adapted as tractors or carriers for the lighter natures of artillery. These vehicles are considerably cheaper to manufacture than most of the tractors which have previously been tried, they are good across country, and it seems likely that they will be suitable for commercial purposes in peace, especially in undeveloped countries.
The French, in 192o, proposed to introduce an agricultural tractor, encouraged by a Government subsidy, which should be available for the transport of artillery. But it was found that owing to the small size of fields in France there was little demand for the tractor, and no immediate prospect of its superseding the horse. On the other hand, the use of motor lorries is extending rapidly. The French now carry the field artil lery, which is required to be highly mobile, on lorries, thus accept ing the principle of the carrier, not the tractor. These lorries can not move off the road, except on favourable ground; therefore each battery carries on its lorries some draught horses or small tractors of the Klectrac or Pavesi type to take the guns into posi tion. The French had 83 of these batteries portees at the end of the war.
The Italians are tending to a somewhat different solution. No draught horses are bred in Italy; they have to be imported from Germany. It is therefore proposed that the divisional field guns should be drawn by the Pavesi agricultural tractors already de scribed. The Italian army field artillery, which is required to be highly mobile, will be carried on low platforms, which have springs and rubber-tyred wheels, pulled by fast lorries. When the guns have to leave the roa i, they will be taken into position by the divisional Pavesi tractors.
In the United States the caterpillar tractor, generally of stand ard commercial type, has been adopted for tractor-drawn artillery. For rapid movement over good roads experiments are being made of truck transport of light and medium field artillery, both wholly by truck and by combined truck and trailer.
Medium guns are usually tractor-drawn, the gun being shifted to a "travelling" position in which the weight is divided between the gun wheels and limber wheels. Heavy guns are transported on special wagons, drawn by tractors, which carry the piece itself, while the empty carriage is drawn by a second tractor.
Super-heavy artillery is transported almost entirely by rail, though in 1914 the Germans brought up their siege howitzers, divided into separate loads, on special road-wagons. The railway mounting consists of a massive platform supported by bogies, on which the gun mounting is built. (See Pl. II-7.) In the English Elswick type the gun is fired while the mounting is "alive" on its wheels; in other types the central platform is lowered on to the rails before firing. All-round fire from the truck, without spe cial preparation, is only possible with medium guns ; for heavier natures the gun is laid for direction by running the truck up or back along a curved siding. Or, in some railway mountings, the gun track is supported laterally by heavy "outriggers" sunk in the ground.
For the heaviest natures the railway is used for transport only, and the gun is lowered on to a previously built platform. Perma nent concrete platforms were used in 1914, but these were super seded by "caisson" platforms consisting of iron boxes bolted together and filled with earth, surmounted by a steel platform plate which carried the mounting. Recent American platforms dispense with the caissons, and consist of the platform plate only; this is divided into sections for transport, bolted together on the spot, and pegged down with a number of steel stakes. These platforms can be laid in a few hours, this being a great addition to the value in the field.
Railway mountings can be used for the transport of artillery on light railways, and even on trench railways. Additional narrow gauge wheels are fitted to the gun track for this purpose. In this case a platform must be used for firing. The limit of the height and width of a railway mounting is the loading gauge of the rail ways on which it may have to be used; this depends principally on the size of the tunnels. Practically there is no limit to the length or weight. (X.) Artillery, unlike other arms, is not fully committed once it has become engaged with the enemy, but retains, in great measure, its liberty of action. Without change of position, its fire can be concentrated or dispersed at will, at varying degrees of intensity, on widely distributed targets. It can be disengaged from the com bat with greater facility than any other arm, and, being capable of manoeuvre within striking distance of the enemy, it can be brought again into action in other parts of the battle-field while the fight is still in progress. These important characteristics govern the organization and distribution of artillery in the field. The system must be elastic in order to permit of centralization or decentralization of control according to the situation; and it must allow of the main strength of the guns being collected at points where decisive blows are to be struck.
The smallest unit of artillery is the battery, the composition of which is calculated on the assumption that its guns are normally worked together. A battery of artillery com prises three elements, viz.—materiel—guns, carriages, ammuni tion and stores; personnel—officers, non-commissioned officers, gunners or cannoneers, drivers and artificers; and transport— horses or other animals, motor or other mechanical vehicles, or rail. The number of guns in a battery varies in different countries and in different types of artillery between four and eight though some railway batteries have only two guns (howitzers or mortars) ; in the British army horse and field batteries have six guns or howitzers in war, anti-aircraft batteries eight, and all others, except super-heavy batteries, have four. Mixed batteries of howitzers and guns no longer exist. The vehicles of a battery include carts, wagons or lorries for the transport of ammunition, stores, provisions and forage. The organization and interior economy of a battery are much the same in all artillery. In the British army the command is held by a major; the second in command is a captain. The battery is divided into sections of two guns each, each under a subaltern officer. A section consists of two sub-sections each comprising one gun with its transport and men, and at the head of each sub-section is the "No. i" of the gun detachment, usually a sergeant. In horse-drawn artillery the drivers ride the near horses of their respective pairs, each gun and each wagon being drawn by teams of from four to eight horses. On the march the gunners are usually seated on the battery vehicles. In horse artillery, however, the gun detachments are mounted and in light or mountain artillery, drivers and gun ners march on foot. In addition to the gunners and drivers there are men specially trained in signalling, range taking, etc., in all batteries, who are either mounted or provided with some form of independent mechanical transport such as motor bicycles or cars.
Great Britain the unit next above the battery is the brigade. In the United States two or three batteries are combined in a battalion commanded by a major; two or three battalions into a regiment commanded by a colonel; and two, three or four regiments into a brigade commanded by a brigadier general. The higher units in other armies are groups or battalions of three or more batteries, two or more groups or battalions usually forming a regiment. These units are distributed to armies, corps and divisions in the same way as units of other arms. Horse artillery is the artillery which supports the cavalry; in Great Britain one brigade of three batteries is allotted to each cavalry division; in 'the United States one regiment of six bat teries (two battalions) is allotted to a cavalry division at war strength. In Great Britain field and light artillery together form the artillery of the infantry division. The British divisional artil lery consists of three field brigades, each of three gun batteries and one howitzer battery, and one light brigade of three batteries. Non-divisional field brigades, called army field brigades, are also provided to form a reserve of field artillery at the disposal of the commander-in-chief. Army field, medium, heavy, super-heavy and anti-aircraft artillery are at the disposal of the commander in-chief. . Medium and heavy artillery are normally allotted to corps, super-heavy artillery to armies. Heavy and super-heavy artillery have not usually the complete and permanent organiza tion that distinguishes the lighter natures of artillery and are generally organized, on mobilization, from units of coast artillery. (For natures of guns and howitzers in each class of artillery, see page 469, TYPES OF ARTILLERY.
In the United States pack and light field artillery are assigned to the cavalry division ; light field artillery to the infantry divi sion; medium and heavy field artillery to the army corps; light and heavy field artillery to the G.H.Q. artillery. The field army has no organic field artillery. The approved organization of the division field artillery brigade comprises two regiments of light guns and one regiment of light howitzers.
In the French Army one regiment of 75-mm. guns and one regiment of 155-mm. howitzers is allotted to each division, two "groupes" of I05-mm. guns and two "groupes" of i55-mm. guns to each army corps, and the remainder of the artillery forms a reserve generale d'artillerie which is commanded by a general de division. The infantry organization includes 37-mm. guns and Stokes mortars for close support. In the United States army two regiments of field guns (75-mm. or i 8-pdr. ), forming together one brigade, are allotted to each infantry division, but there is no fixed allotment of field howitzers. The infantry organization includes 37-mm. guns as well as mortars for close support. The corps and higher organization is similar to that of the British and French armies. A comparison of the various organizations out lined above will show that there is considerable variation in the number of field pieces allotted in different countries to an infantry division. Thus 72 are provided per division in the American, 6o in the French and 72 in the British army. On the other hand the number of pieces at the disposal of corps and army commanders generally varies in inverse proportion to the strength of the divisional artilleries, so that the total numbers available per too rifles do not differ greatly.
In each British division an artillery officer of the rank of brigadier is in executive command of the artillery of the division. There is. also a brigadier in command of the artillery of each corps and under him is a commander of the corps heavy and medium artillery. The corps artillery commander commands the divisional artilleries for special deliberate operations only. He is provided with a counter-battery staff whose task is to deal with the hostile artillery. At each army headquarters there is a major-general R.A. whose duties are mainly advisory. The system of command in Continental armies is similar. In the United States each brigade is commanded by a brigadier general. In addition to the brigade commander, there is a chief of artillery both in the corps and army.
Certain auxiliary organizations are now required by artillery. In the British army artillery survey work is carried out by survey companies which are also responsible for sound-ranging and flash-spotting. Signal units are provided by the Royal Corps of Signals down to headquarters of brigades, batteries being responsible for their own signal communications. Searchlight battalions of the Royal Engineers are provided to co-operate with anti-aircraft artillery. In the United States flash and sound ranging are functions of the field artillery, as are signal commu nications within the field artillery brigade. The organization for the supply of ammunition is described in a separate section. In addition to the normal chain of artillery command provision is usually made for technical control of the materiel, and a variety of training and experimental establishments, such as schools of gunnery, are maintained by the military authorities in most countries.
In the British army all the personnel of the artillery arm in the field, as well as of the coast artillery, is provided by the Royal Regiment of Artillery. Officers and men are transferred from one class of artillery to another at intervals of a few years in order that their training may be comprehensive. In some armies as, for example, the army of the United States, the artillery service is divided into two branches, the field artillery being distinct from the coast artillery corps.
The actual process of coming into action may be described in a few words. The guns are "un limbered" at or near the battery position and the gun limbers and teams or tractors sent back under cover. An ammunition wagon (caisson) or lorry is then placed, as a rule, by the side or in rear of each gun, an arrangement which simplifies the supply of am munition. According to the British practice a battery in action is thus distributed : first the "firing battery" consisting of the guns, each with its ammunition vehicle ; then, under cover in rear, the "first line of wagons" comprising teams or tractors of the firing battery, the gun limbers and the remaining ammunition vehicles. The non-combatant vehicles form the "second line of wagons." Choice of a Position.—The nature of the position to be occu pied depends primarily upon the task which is to be carried out. Although "open" positions may have to be occupied on occasions, they are generally to be avoided since guns are quickly silenced in modern war if they come into action in full view of the observing posts of the hostile artillery. As a rule, therefore, artillery use posi tions concealed from view behind a ridge or other cover, the eleva tion and direction necessary to hit the target being signalled by an observer who may be either on the ground or in the air. The choice of the position varies to some extent with the nature of the equipment ; for instance, an elevated position is better adapted than a low one for high velocity guns on account of their flat trajectory. Other factors which have to be considered are (a) the desirability of a field of fire immediately in front of the guns for shooting at hostile tanks; (b) concealment from air observation; (c) avoidance of ground in which pockets of gas might lie; (d) approaches for ammunition supply. It is usually possible, however, to satisfy only the more important requirements in each particu lar situation. Cover from hostile fire, as distinct from observation, cannot often be obtained from the configuration of the ground, because, if a gun can shoot over a covering feature, the hostile shells can also clear it. Most of the lighter types of artillery are therefore provided with shields which, with the armoured ammuni tion wagons (caissons), afford some measure of protection to the guns and detachments. Guns are usually brought into action about 20 to 25 yd. apart, this interval being considered sufficient to minimize the damage which may be done by hostile shell fire.
This process serves to determine the elevation at which a gun will hit the target, or, more correctly, the elevation at which the greatest possible number of shells will fall on the target. This elevation is not necessarily that due to the map range, as it is affected by the temperature, height of barometer, strength of the propellant, degree of wear of the gun and other factors. When a number of shells are fired from a gun which is pointed at a given elevation, they do not fall in the same place, but are dis tributed over a space which, at medium ranges, may be ioo yd. or more in depth. The centre of this space is termed the "mean point of impact." The first step in ranging is to determine, by observation of the fall of the shells, two elevations, usually 300 400 yd. apart, at the higher of which shells will fall beyond the target, and at the lower of which they will fall short. These two elevations constitute the "long bracket," within the limits of which the true elevation must lie. This bracket is then "split" by firing at the two intermediate hundreds of yards, and observing the results, thus obtaining a closer approximation to the elevation required called the "short bracket." Finally, corrections of Boyd. or less are made until an equal proportion of rounds are observed to burst over and short. Ranging for line, that is, for lateral direc tion, is carried out in the same way, and generally simultaneously with ranging for elevation. When time shrapnel is used it is also necessary to determine by observation the length of fuze which will give bursts at the most effective height above the ground.
It is possible to open effective fire by surprise without preliminary ranging, if the range and line can be obtained by measurement from accurate large scale maps or, in the absence of such maps, by "fixing" the positions of guns and targets by survey methods. For such "pre dicted" shooting certain meteorological and other information is necessary to determine the corrections which must be applied to the true range and line. A special section in each army corps, known in the British Army as "Meteor," keeps the batteries in formed as to atmospheric conditions. The guns must be carefully "calibrated," a process which consists in determining the error due to wear at a known range. Survey methods cannot generally be used in very mobile operations owing to the time required to carry out the necessary preliminary work.
This is effected by observing the moment at which the sound of the burst of the shell reaches each of a chain of recording instruments. It has recently been improved so as to give very accurate results under suitable weather conditions from a set of instruments occupying as little as 2,500 yd. of front. The setting up of the instruments takes the rather lengthy time of from 24 to 48 hours, which limits the employment of this method in mobile warfare. It is of particular value in trench warfare for locating hostile guns by means of their reports.
"Elevation" may be defined as the vertical inclina tion of the gun, "direction" as the horizontal inclination to the right or left, necessary to direct the path of the projectile to the object aimed at. In order to lay the gun in the "line of sight," i.e., the line joining the sights and the point aimed at, the gun has to be "traversed"' right or left so as to point in the proper direction, and also adjusted in the vertical plane. The simplest form of laying is called the "direct" method, which is employed if the point aimed at is the target and can be seen by the layer. He has then merely to look over or through the sights. But the point laid on is rarely the target itself. In war, the target, even if visible, is often indistinct, but in most cases, it cannot be seen at all from the gun position. An "aiming point," a conspicuous point quite apart and distinct from the target, has then to be employed ("in direct" method). When the guns are behind cover and no natural aiming point can be seen, an artificial aiming point is often made by placing a line of "aiming posts" in the ground. An alternative to aiming posts is now provided by the "paralleloscope" which is a mirror set up a few feet from the gun. When this device is used the layer keeps the gun in the correct line of fire by laying upon the reflection of the sights in the mirror. Finding the "line" in the case of indirect laying involves the calculation of the angle at which the guns must be laid in order that, when the sights are directed upon the aiming point, the shell will strike the target. When a gun is laid for elevation by the indirect method, two angles to the horizontal plane have to be allowed for, viz., that due to range and that due to the difference in level between the gun and the target. The latter is called "the angle of sight." When the target is above the level of the gun, the angle of sight has to be added to the elevation due to the range; when the target is below the level of the gun the angle of sight has to be deducted. In all cases the actual elevation of the gun to enable the shell to strike the target is a purely mechanical adjustment, the gun being moved to the required angle with the aid of an elevation indicator or a clinometer. Frequently the battery commander directs the guns from a point at some distance, communication being maintained by signallers or by field telephone. Instruments of precision and careful calculation are, of course, required to fight a battery in this manner, many allowances having to be made for the differences in height, distances and angle between the position of the battery commander and that of the guns.
Fire.—In the British service three methods of fire for effect are used within the battery. These are : Gun fire, in which the guns fire independently at any rate which may be ordered; Battery fire, in which the guns fire in succession throughout the battery ; Salvo fire, in which the guns are fired simultaneously on the order of the gun position officer.
The application of fire by batteries acting in combination is dealt with in section on TACTICS.
Shrapnel, which is fired by most guns and in some cases by howitzers, is used against troops in the open, for offensive and protective covering fire and for general harassing purposes. The forward effect of the bullets makes it especially effective when fired in enfilade. High explosive shells with instantaneous fuzes, which are usually fired in addition to shrapnel by all natures of guns as well as by how itzers, are also used against troops in the open and for covering and harassing fire. They are further employed for wire cutting, for engaging troops under light cover and against tanks. High explosive shells with graze and delay fuzes, are used against troops in trenches and for the destruction of buildings and other strong cover. High explosive shells with time fuzes are used against air craft. Smoke shell are employed for screening effect, to mask hostile fire and to deny observation to an enemy. Star shell are sometimes used for purposes of illumination, but they are not of great value in mobile warfare. (For description of the various types of projectiles see AMMUNITION.) Signal Communications.—The methods at present employed on the ground are line telephony, using voice or buzzer, and visual signalling. Aircraft communicate with batteries by means of wire less telegraphy and batteries with aircraft by means of wireless telegraph and panels, i.e., strips of white cloth which are laid out on the ground. Radio telephony is being developed by most countries but it has not yet reached the stage of practical utility in the field.
may be done by the battery commander himself, by a special "observing" party or by an observer in an aeroplane or balloon. The difficulties of observation vary consid erably with the ground, etc., for instance, the light may be so bad that the target can hardly be seen, or again, if there be a hollow near the target, a shell may burst in it so far below that the smoke appears thin to a ground observer, the round then being wrongly judged "over" or "short," or lost altogether. Smoke is often used in ranging with air observation to facilitate picking up the rounds. Observations from the air are signalled to batteries by wireless, some form of code being employed by which the fall of rounds can be plotted on a chart.
In 1914 it was considered that Soo rounds per field gun should be in hand in the theatre of war at the beginning of a campaign, with a reserve of i,000 rounds per gun in the arsenals. It was found that this allowance was absurdly inadequate even in the more mobile phases of the World War. For great attacks on en trenched positions it was necessary to employ one field gun per ioyd. on fronts of many miles, and each gun was frequently re quired to fire Soo rounds or even more in a day. It was therefore essential to increase the scale of manufacture and to revise the methods of supply. The solution of the problem of supply was found in the development of the use of motor transport and, for periods of trench warfare, of light railways and specially laid trench railways.
Since 1918 a new system of ammunition supply has been intro duced in the British army which will allow of a more abundant and rapid supply of ammunition in mobile warfare than ever be fore. Maintenance companies, under corps control, carry ammuni tion from railheads to ammunition companies, under divisional control. These, in turn, deliver to batteries or, alternatively, to horse-drawn divisional ammunition columns. Maintenance and ammunition companies are composed of motor lorries and have respectively a radius of action of 25 m., so that guns can be served over 5o m. from railhead. The divisional ammunition column (horse-drawn) is regarded as a mobile reserve of ammuni tion for the divisional artillery and is used as a link in the chain of supply only when lorries of the ammunition companies cannot deliver direct to batteries, e.g., when the battery positions are on difficult ground away from roads. Army field brigades and horse artillery brigades have special brigade ammunition columns whose functions are similar to those of the divisional ammunition columns.
Some ammunition vehicles, which are usually lightly armoured, are also included in the batteries themselves. The number of rounds carried by them varies from ioo to about 30o per gun in different types of artillery. The greater the amount of ammuni tion a battery carries with it, the more independent it is ; on the other hand, every additional wagon or lorry makes the battery more cumbrous and, by lengthening columns, increases difficulties of manoeuvre and deployment. Formerly the artillery was ham pered by having to carry the reserve of small arms ammunition for infantry and cavalry, but this is no longer the case. When it is anticipated that the expenditure of ammunition in an operation will be greater than can be replaced immediately, dumps are usually placed at the guns or in suitably advanced positions; and, in a retreat, ammunition should also be dumped where it can be picked up by batteries as they withdraw. This latter expedient was used successfully by the British in the retreat from Mons in 1914.
In the army of the United States the field artillery battalion has a combat train which carries reserve ammunition; the field artil lery brigade has an ammunition train ; and the corps and army have ammunition trains. Ammunition supply is normally from the army to divisions.
In the French Army ammunition is conveyed from railheads (gares de ravitaillement) to delivery centres (centres de livraison) or advanced depots by motor transport units of armies. It is then conveyed to batteries by lorries of the corps artillery park (pare d'artilleries de corps d'armee), transport of the corps heavy groups, horsed and motor vehicles of the divisional artillery park sections and group ammunition columns. The main feature of the French system is its flexibility, the various transport units in the forward area usually being under the control of corps for use in the way best suited to each situation. In the American army corps trains of motor transport supply ammunition to brigade ammunition columns which may be mechanized or horsed.
In modern war it is found that infantry, in face of opposition, are immobilized and driven to seek cover as soon as they get within the zone of the enemy's aimed rifle and machine gun fire. Attacking troops can only continue to advance—(and without ad vancing no decision can be gained)—by enlisting the aid of an arm which is capable of keeping down the enemy's fire while itself remaining sufficiently immune by reason of the distance from which it can operate, or by armoured protection as in the case of tanks. At present the artillery affords the principal means of dominating the enemy's fire. The advent of tanks has, however, profoundly affected the role of artillery in battle and the new tac tics have not yet been fully evolved. Tanks are capable of re lieving the artillery of various forms of support required by in fantry and cavalry, but tanks themselves require artillery support if they are not to suffer heavy casualties. The capabilities of the tank have not yet been completely determined, nor can they be until design has reached a greater degree of finality and further war experience has been gained. Further, the relative position of tanks and artillery is becoming confused since some of the most modern types of armoured artillery on self-propelled carriages are themselves but tanks under a different name. The process of mechanization of artillery transport, which is still in progress, also affects the employment of artillery. Artillery tactics are, there fore, at the present day in the midst of a period of evolution. Many of the statements which this article contains will be subject to considerable modification in the near future.
Developments during and since the World War have greatly in creased the range, accuracy, fire power and mobility of artillery. A further important advance has been in methods of survey. There are certain limitations to the full development of the power of artillery, the most serious of which is perhaps the difficulty of including in mobile formations sufficient artillery to break down modern defences, and of supplying it with ammunition. Another important limitation which is still engaging the attention of mili tary authorities in all countries is the unsatisfactory nature of the means of signal inter-communication at the disposal of modern artillery. Good signal communications between artillery com manders, their guns, and the troops they are supporting are of vital importance.
The principles of surprise, concentra tion and economy of force (i.e., economizing strength while com pelling dissipation of that of the enemy) are generally held to be of special importance in the application of artillery fire. To ob tain surprise it is necessary first to conceal the concentration of the guns and the occupation of positions. In order to evade de tection by hostile aircraft, large movements of artillery are now generally carried out at night. Should they be carried out by day, skilful use of cover is necessary to screen movement from ob servers on the ground. Once the guns are in position, care has to be taken not to disclose their position by firing prematurely and, to this end, the survey methods of working out lines of fire and ranges, already alluded to, are of particular value, as the warning which used to be given by preliminary registration can be elimi nated by their adoption in certain circumstances. There is, further, considerable scope for exploiting the value of surprise after the presence of the guns has been disclosed by the opening of fire. Stereotyped systems of shooting should be avoided and damage and casualties increased by bringing fire to bear on the enemy at unexpected times and places and in unexpected ways.
Concentration of effort is as essential in the employment of ar tillery as in the case of any other arm. The maximum amount of fire must be directed upon the targets which are of greatest im portance, and bombardments should be intense and short rather than weak and prolonged. The best means of securing concentra tion is to centralize command, and it is thus a general principle that control should be vested in the highest commander who can exercise it effectively in any given situation. For effective control, a commander must be in communication with the guns and in touch with the ever-changing situation of the troops he is support ing. When operations are of a deliberate character, inter-communi cation is comparatively easy to maintain and information is fuller. Control may then be exercised from divisional or even corps headquarters. In very mobile operations, however, artillery bri gade or battery commanders will often have to act upon their own initiative, subject to broad instructions from their superior corn mander.
The maintenance of the principle of concentration involves a strict observance of the allied principle of economy of force. Ar tillery should be economically allotted to its various tasks and where possible a reserve should be formed. The various types should be employed against the targets they are designed to en gage. Thus it would be wrong to use a powerful weapon for a task which could be equally well performed by a less powerful one the life of which is longer and its ammunition more easily supplied. Fire should never be opened without a definite object, and the expenditure of ammunition should be proportionate to the tactical importance of the task. Economy is further obtained by accuracy of fire, but occasions arise when some degree of accuracy may have to be sacrificed to save time and to ensure surprise.
Whenever possible, artillery fire is directed by observation. Observation may be carried out from the ground or from the air. Ground observation is most suitable for shooting on targets on the immediate front of friendly troops, and observation posts are selected, whenever possible, so that they may overlook the foremost elements of the troops who are being supported as well as the areas in which targets are to be engaged. Observation from air-craft is largely used for counter-battery work, for fire on distant targets and for dealing with vulnerable and fleeting tar gets which cannot be seen from the ground. In the British army the requirements of the artillery in air observation are met by army co-operation squadrons of the Royal Air Force. These squadrons also provide photographs of the enemy's positions and rear organization which are of great value in the discovery and selection of targets. Balloons are also used for purposes of ob servation, but they are handicapped by their vulnerability and the distance from the enemy at which they must operate (see also under TECHNIQUE).
As the role of the artillery is to support the other arms, its action is governed by their re quirements. The question of co-operation with the other arms is, therefore, one of special importance. Artillery officers of all ranks have to keep themselves informed of the general situation and plans of commanders whom they are supporting. The best means of ensuring good co-operation is for headquarters of artillery and of units with whom they are co-operating to be in close proximity. Liaison officers are also used to aid in keeping touch, and artillery patrols may be sent forward to supplement personal reconnais sance and the information furnished by artillery observers. The artillery frequently has to rely on close reconnaissance aeroplanes or on rockets or other special signals for information of the situ ation of the forward troops. The other arms are trained to supply constant information to the artillery as to their movements and the obstacles which they encounter ; this information is essential if artillery support is to be effective. Another important aspect of co-operation lies in the co-ordination of the action of the artillery with that of the weapons of the other arms. For example, artil lery fire must be directed in such a way as best to supplement the fire of machine guns and the action of tanks.
In the attack the object of the artillery is to assist the other arms to maintain their mobility and offensive power. Its tasks may be summarized as follows :—(i.) artillery preparation, (ii.) covering fire, (iii.) close support, (iv.) counter-battery work, (v.) harassing fire, (vi.) co-operation in pursuit.
An army advances against the enemy cov ered by the advanced guards of its several columns. During the approach march some light, field and possibly some medium artil lery will usually be allotted to the advanced guards whose duty it is to drive in the enemy's protective troops by bold and vigorous action. If the artillery allotted to the advanced guards proves in sufficient to overcome the enemy's resistance it may be reinforced from the main bodies. If the enemy is in strength a stage will be reached when the advanced guards will no longer be able to ad vance and when the main bodies or portions of them will be de ployed. A plan of attack will then be formed by the commander of the force. If the enemy has been met on the move, or found in a hastily occupied position, the situation will call for rapidity of action, as the dominant need will be to prevent him from seizing the initiative or strengthening his defences. If, on the other hand, he is in an organized position strengthened by artificial defences such as wire entanglements, trenches, field works, etc., the attack cannot be launched without deliberate and methodical arrangement and it must be supported by a strong concentration of artillery.
In disposing the artillery, the governing con siderations are (i.) concentration of the maximum fire to assist the decisive phases of the attack; and (ii.) ability to support the advance to as great a distance as possible without moving the guns. This last requirement entails siting the guns well forward, the most advanced field guns being as a rule no further behind the leading troops than is necessary to obtain cover and to clear the heads of the infantry.
The artillery plan comprises the scheme of fire and the arrangements for command, control, communications and move ment of artillery in support of the advance. A commander will often have to decide whether it is important or not to use the full power of his artillery in his attack. To develop its full strength the artillery may often require more time for preliminaries than the other arms, and a plan of attack may suit it which does not best suit the other arms. In such a case a commander will gen erally treat his artillery as the predominant arm if the enemy's defences are strong.
Artillery preparation consists of the bombardment of the en emy's defences before the attack is launched, its objects being to inflict loss and damage, to cut wire obstacles—if tanks are lacking —and to undermine moral. If the enemy's positions are not strong or if tanks are available, artillery preparation may be dis pensed with and surprise ensured thereby. If it is undertaken it should be as short and heavy as possible.
Covering fire may take the form of a barrage (i.e., a belt of fire) moving ahead of the assaulting troops; of concentrations upon successive localities; of smoke screens; or a combination of any or all of these forms of fire. A barrage has some measure of destructive and neutralizing effect on all troops on the ground over which it passes. It is the simplest method of giving support when the enemy's positions cannot be located with accuracy—and in modern war this is the normal state of affairs, owing to the diffi culty of seeing machine-gun posts, etc. Objections to the bar rage are that it is wasteful of ammunition and that the guns avail able in modern armies permit of this form of support in very in adequate measure. A very thin barrage can be provided by one field gun to 3oyd. of front, but even this diluted form of barrage cannot be provided by the divisional artillery for more than a very short time nor over more than a small fraction of the divi sional front, e.g., in the case of the British division it could be provided on about one-eighth to one-tenth of the frontage occu pied by the deployed infantry, the remainder of the frontage being denuded meanwhile of artillery support. It is therefore obvious that, in face of strong opposition, reliance would have to be placed upon considerable reinforcements of army artillery units or upon tanks to supplement the action of the artillery. In the provision of covering fire, field guns are used as a rule to shoot nearest the assaulting troops, who are trained to move as close to the bursting shells as possible; field howitzers and medium artillery are used to give depth to the fire and to shoot on more distant targets. As a rule covering fire is arranged in its early stages according to a time-table based on the expected rate of advance of the troops, subsequent support being given by observed fire from guns ad vanced if necessary during the fight.
Smoke shells are fired by artillery in conjunction with other types of ammunition or alone. The principal use of smoke is to furnish concealment to attacking troops in order to enable them to move unobserved for the purpose of effecting surprise. By its use an attack can get to close quarters without being seen and smoke clouds can often be so disposed as to enable the assault to be launched from an unexpected direction. Smoke screens may also be used to conceal the movement of reserves. Smoke is also of great value to reduce casualties among the assaulting troops by preventing the enemy's fire from being aimed or observed, and it should therefore be the object of the attacker to use it in such a way as to blind artillery observation posts and to mask machine gun positions, strongly defended localities, and anti-tank weapons. Smoke screens may also be put down by artillery to protect open flanks, or to prolong a front of attack and so induce the enemy to disperse his fire. Other uses for which smoke shells are some times employed are to assist attacking infantry to maintain direc tion by marking objectives or boundaries between formations, or to signal and co-ordinate the time for the resumption of an advance after a pause on an intermediate objective.
The tendency of an enemy, when a smoke cloud is put down, is to pour a heavy fire into it and this fact has to be borne in mind in evolving plans for its employment. The actual production of a smoke screen requires great skill and the wind and weather have to be carefully considered. If smoke is fired indiscriminately it may interfere seriously with observation from both ground and the air, with reconnaissance during battle, with signalling or with operations of troops on the flanks.
The prearranged covering fire may not be sufficient to overcome all resistance to the advance and leading units therefore have to be accompanied by some artillery to ob viate the delay which would be entailed in signalling to guns at a distance. So much is generally admitted; but the nature, com mand and organization of the accompanying artillery are mat ters on which opinions differ. Moreover, the infantry are not satisfied with guns of accompaniment, but demand a weapon of their own in the actual firing line to deal with tanks. It is im possible to go into the whole controversy in this article.
The British gun of accompaniment is at present the 3.7-in. light howitzer, but this weapon is generally considered too large and its shell is so heavy as to present serious difficulties in ammunition supply. Field artillery is also used for close support to replace or reinforce the light howitzers. The French infantry organization includes 37-mm. guns and Stokes mortars, but they also favour the employment of the 75-mm. field gun which may be provided with a special low carriage and taken into action by a small tractor. Other nations have introduced pack guns or special light guns or howitzers which can be drawn as far forward as possible by small tractors and can then be divided into loads and carried up by hand. Experiments with various kinds of equipment are being carried out in most countries. It will be difficult if not impossible, to combine in one weapon the requirements of close support, which call for a comparatively heavy shell and a curved trajectory, and those of an infantry anti-tank gun, which demand a flat tra jectory, a rapid rate of fire and comparatively small calibre. It therefore seems probable that two weapons will be evolved, both mobile, and possibly carried or drawn by small armoured tractors, but one in the nature of a small howitzer for close support and the other in the nature of a heavy machine-gun capable of stop ping tanks up to i,000yd. or i,5ooyd. range.
comprises the location, neutraliza tion and, when possible, destruction of the enemy's artillery. The problem of dealing with the hostile guns is given much greater attention in all armies than was the case before the World War. It now enters into operations of every kind and in varying degrees lies within the sphere of responsibility of every artillery com mander. Special counter-battery staffs are generally provided at corps headquarters. The chief sources of information as to the enemy's artillery are (i.) observers in aircraft ; and (ii.) flash spotting and sound-ranging units on the ground. In addition, artil lery and infantry observers are trained to send back information. A portion of the attacker's field and medium artillery is usually allotted the task of engaging the hostile guns before and during an action with the object of keeping down their fire and so facilitat ing the advance of the assaulting troops.
The objects of harassing fire are to wear down the enemy's fighting spirit, to inflict casualties and damage upon him, to prevent movements of reinforcements and ammuni tion and generally hinder the conduct of the defence. Harassing fire has to be reduced to a minimum in mobile war owing to the small quantities of ammunition which are available ; in deliberate opera tions or static warfare there is great scope for its development.
During an advance artillery is pushed forward to support the infantry and to assist them in pressing the enemy, batteries usually being moved alternately within brigades so as to ensure that the covering fire will be continuous. But to obtain decisive results in a pursuit it is necessary to launch against the enemy a special pursuing force, composed of mobile troops. Mechanized artillery is of special value with such a force, and it should be handled with the greatest boldness, risks being accepted which would not be justifiable at other times.
In defence the artillery assists in the protection of the other arms and co-operates with them in repelling the enemy's assaults. Its tasks may be summarized as f ollows :—(i.) counter prepara tion, (ii.) fire to repel assaults, (iii.) anti-tank defence, (iv.) counter battery work, (v.) harassing fire.
In defence the artillery has to be sited in such a way that it will be able to bring the full weight of its fire to bear in front of the line of infantry defences on which the commander intends to stop the enemy. In mobile war the infantry defensive position will generally consist of a chain of defended localities, and it will usually be in front of this line that the artillery will be required to shoot in order to break up an assault. In more deliber ate operations, however, time and resources may permit of the defensive position being more highly organized. It may then con sist of a lightly held forward zone, intended to absorb the first shock of a heavy attack, and a strongly held main zone in which the battle is to be fought out. In this type of defence the bulk of the artillery has to be sited further back with the object of bring ing the main weight of its fire to bear in front of the main zone, a small proportion only of guns being allotted to support the troops in the forward zone. This method of defence was exploited by Petain in stopping the final German offensive of July 15, 1918, and it has found much favour in the eyes of soldiers. The bulk of the guns are not sited in such advanced positions in defence as in attack for two reasons, firstly, that they may not be easily neutral ized by the attackers' artillery, and, secondly, that they may not be over-run in the first rush of an assault. A proportion of the guns must be in forward positions, however, for the purpose of engaging the enemy's artillery and rear communications and of hindering arrangements for an attack. The fulfilment of these re quirements results in the defender's artillery being distributed in depth. An important factor which must also be considered in dis posing the artillery is the problem of anti-tank defence. This is discussed below. An essential requirement of defensive positions to be occupied by infantry, besides facilities for siting the guns, is suitability for artillery observation. It is always desirable that there should be some rising ground from which observation can be carried out, and such localities should be so far behind the fore most defences that they will not be captured, and the eyes of the defence blinded, by a minor penetration by the enemy.
The artillery plan of defence comprises, besides the arrangements for dispositions, which are discussed above, the scheme of defensive fire and the policy which is to govern counter battery action. Surprise is as important in defence as in attack and it is therefore important that the fire plan should not be dis closed prematurely. A favourite device is to keep as many as possible of the defending guns silent until an attack develops and then to engage the enemy with an unexpectedly heavy fire. In order to conceal the battle positions of the defending artillery, guns which are required to be active often shoot from temporary positions which they vacate before the enemy's attack is launched. It is important to make arrangements to concentrate as much as possible of the available artillery fire on any particular portion of the front which may be attacked by the enemy and to make all possible preparations to support counter-attacks. Smoke has to be used with caution in defence as it is liable to obscure the view of the defenders and so to hamper their fire.
Counter-preparation is the term applied to fire which is deliv ered with the object of breaking up an attack before it can be launched. It is directed against probable forming-up places and forward communications in order to disorganize the enemy's troops when they are suspected of being about to assault. A plan of predicted fire is usually arranged as soon as a defensive position is occupied but, if the enemy's troops can be seen and signal com munications can be maintained, it is more effective to shoot with direct observation.
Once an attack is launched it becomes the aim of the artillery to direct fire on the assaulting troops and reserves. It is desirable that, as in the case of counter-preparation, such fire should be controlled by observation, but this is not often practicable. Attacks may be launched under cover of smoke or in the half light of dawn, and signal communications may be cut by hostile fire; even when other conditions are favourable, observa tion will be rendered impossible when there is such a force of artil lery that observers are unable to distinguish the shells of their own batteries. It is therefore a rule to detail targets to be engaged by all batteries with predicted fire. Such targets will generally be the most probable lines of approach for the enemy and other vulner able portions of the front, and the fire of the guns must be care fully co-ordinated with that of the infantry weapons, especially with that of machine guns. The artillery resources of present armies will not permit of continuous belts of artillery fire being placed in front of the infantry positions as was done in the World War, and it is not to be expected that sufficient resources will be forthcoming in the future for the resuscitation of the "standing barrage" unless periods of static warfare recur.
A considerable share of the responsibil ity for anti-tank defence falls upon the artillery. The anti-tank weapons of the infantry are generally reinforced in the forward defences by some light or field pieces which are sited in concealed positions from which they can deliver a sudden fire at short range. A serious objection, however, to the employment of artillery in this task is that guns sited in forward and exposed positions are of little use for general purposes of defence. A second line of defence is formed by the main force of the artillery, all battery positions being chosen as far as possible so as to provide a field of fire against tanks. In addition, some guns have to be disposed for the protection of headquarters and other important points in rear.
Counter-battery work is generally carried out by the defenders with the object of weakening the hostile artillery before an assault can be launched. Once the attack develops, however, it may be preferable to direct the full power of the defending artillery for a time upon the assaulting troops.
In a defensive action of a temporary nature this form of fire will not generally be developed owing to the necessity for economizing ammunition. When resources permit, however, an enemy's offensive preparations may be considerably hampered by a well devised scheme of harassing fire.
When a force is retiring in face of an enemy, mobile artillery is of particular value for covering the withdrawal of the other troops. Thus rear guards usually contain a large pro portion of guns. Enemy columns should be engaged at long ranges with the object of forcing them to halt and deploy as frequently as possible. Command of the artillery will generally have to be decentralized to infantry brigades or corresponding units in this form of operation, and batteries should retire alternately in order that continuous support may be provided.
