JOURNAL OF THE ATTACK.
98. In connection with the plan of attack previously referred to (par. 78), a complete Journal of the Attack will be kept in which will be recorded day by day a detailed record of the daily progress of the siege, giving the day and hour of starting and completing each battery, parallel, approach, etc., with their daily progress, dates of opening fire from each battery, and, generally, every incident connected with the siege. This journal will be supplemented by journals kept by the chiefs of engineers and artillery, in which will be consolidated the daily reports of all subordinate commanders of these respective arms, giving the expenditure of ammunition, the performance of the guns, carriages, etc.; the modification made in details of parapets, batteries, magazines, etc., with their value; the results of trials of new devices, and special reports upon any points connected with the siege. These journals will be carefully preserved and copies transmitted to the War Department from time to time for future use.
CHAPTER VI.
THE DEFENCE.
99. Preliminary Considerations.—The defence of a fortified place is entrusted to a commanding officer, who, when the siege is established, is generally known as the “Governor of the Place.” His duties become more exacting and his powers more absolute from the beginning of hostilities until the place is invested and cut off from communication with the exterior, when, since the whole responsibility of the defence rests upon him, his powers over both the garrison and the inhabitants of the place, of necessity become autocratic in all matters affecting the defence, directly or indirectly. He, of course, avails himself of the counsel and advice of his subordinate officers and may make up a “Council of Defence” from his second in command and the commander of the engineers and of the artillery; but the ultimate decision of all questions must rest with him alone.
During peace and after the beginning of hostilities up to the near approach of the investing force, the civil authorities retain their ordinary jurisdiction, unless martial law is declared by proper authority; but after the place is invested, martial law (or state of siege) exists from necessity, and the police power, the control of provisions and supplies of all kinds, public and private, buildings, animals, vehicles, etc., and everything necessary for the defence of the place fall into the hands of the governor, who also is empowered to direct who shall be sent out and who shall be retained within the place, and what necessary service or labor shall be performed by the inhabitants. Having been selected for these onerous and exacting duties, he, under no circumstances, allows himself to be cut off from his post, and is therefore debarred from leading his troops in person in the active operations outside the work or exposing himself unnecessarily or recklessly during any period of the siege.
100. The Garrison.—The garrison should consist of artillery and infantry, and, in an intrenched camp, of enough mounted troops for escort, messenger, and a limited vedette service.
The strength of the infantry is generally regulated so as to give a suitable garrison to each detached work, and about 1½ to 2 men for each yard of the front of attack. The artillery is allowed about 12 men for each gun. The number of engineers is determined for each place by the probable amount of engineer work that will be required. These troops make up about one-third of the entire force.
A general reserve of all arms (principally, however, foot troops) makes up the other two-thirds, and is held as “a fighting force” for preventing the investment of the place, or for breaking up the investing lines when established. This reserve is called upon for work on the front of attack or in the trenches only when it cannot be avoided.
In smaller places the portion of the garrison called upon for the outer line of defence may be increased to one-half or two-thirds, and the general reserve be reduced to one-half or one-third of the entire force. When the investment is strongly established the general reserve will usually be combined with the other troops.
The troops engaged on the front of attack are usually assigned to the different sectors of attack and are divided into reliefs (ordinarily three), each relief having as a rule a tour of one day in the front lines, one in the immediate supports, and one in the reserve and in interior fatigue duty. The Governor, however, so regulates the details as to impose upon the troops the least work consistent with an energetic defence.
101. Armament.—The guns for arming the place should be placed in position or in store within the works before the beginning of hostilities. There should be mounted in commanding positions a sufficient number of high-power guns to hold the enemy’s first works at a distance and to fire upon his camps, etc., if placed too near. In addition to these, a full supply of light guns, including machine and rapid-fire guns, should be at all times equipped and supplied for immediate use in meeting an assault or surprise. Their emplacements, platforms, etc., should be in readiness for use at any moment.
In large places and for an active defence there will be needed also enough field-guns to properly equip the general reserve (about 4 guns per 1000 men). These should be considered a part of the equipment of the reserve.
It being, from economical considerations, impossible to supply guns to fully arm all the fronts of a place, enough only are usually provided to thoroughly equip the sector of attack and to replace those disabled. These are stored within the place where they are secure against deterioration or injury, and are mounted in the sector of attack when it is definitely determined. The numbers of high-powered guns, howitzers, mortars, and machine and rapid-fire guns needed must be determined from the size of the place, its garrison, and the character of attack which may be expected.
102. Ammunition, Provisions and Supplies.—A plentiful supply of ammunition, especially of projectiles, for all the guns should be kept constantly on hand. The projectiles, which may be stored for an indefinite term without deterioration, may be distributed in magazines in proximity to their batteries; the powder should be so stored as to preserve its properties, and be distributed to the service magazines at such times and in such quantities as may be necessary. Other equipments will be stored and handled in accordance with the same principles.
The utmost care will be taken in storing and issuing the provisions and supplies belonging to the troops; and in cases of necessity during the siege the sales of provisions to the inhabitants by the dealers will be regulated, both in prices and quantities, by the military governor.
103. Sanitation and Hygiene.—The most rigid sanitary measures and rules of hygiene should be enforced from the beginning of the siege, under the direction of the military governor, whose medical officers should join with the health officers of the place (if any exist) in guarding not only the troops but all the inhabitants from all avoidable causes of epidemic diseases. Extreme rigor in carrying out these regulations in not only allowable, but is most urgently required.
104. Preparations for Defence.—An active defence being presupposed, all possible measures for its execution should be taken before the near approach of the enemy interferes with them. The principal ones are as follows, viz.: Advanced posts are established as far from the work as is prudent, say 3500 to 4000 yards, placed at points which may be easily defended or which would be advantageous positions for the enemy’s batteries, etc. These, when possible, should be so placed that the ground between them is swept by their infantry fire and by the artillery of the place. They should be provided with good cover for the troops, and parapets for infantry and field-guns. When not naturally strong, field-works should be built. Quarries, ditches, sunken roads, villages, woods, etc., should be taken advantage of, either as points of defence, passive obstacles, or covers for communications, as may be best. Lines of retreat to the work as secure as possible from hostile fire should be provided. All supplies in the vicinity of the work which will be useful during the siege should be collected and taken into the place. Means of communicating with the exterior by telegraph, telephone, signal flags, lanterns and heliotropes, carrier-pigeons and balloons, should be secured. Search-lights for illuminating the exterior should be obtained, and as soon as practicable bomb-proofs and shelters for the inhabitants should be prepared in the body of the place; and in connection with the civil authorities the fire department of the place should be organized and taught how to extinguish fires with dry earth and by pulling down buildings when water is not available.
The service of security and information should be extended to the furthest possible limit, not only by outposts, etc., but by telegraph operators and reliable correspondents at long distances from the place; and preparations should be made to retard the approach of the enemy by the destruction of the roads, bridges, etc.
105. Defence during the First Period of the Siege.—Upon the approach of the enemy each work should receive its permanent garrison, and the fighting reserve should go out to occupy the advanced posts and to take full advantage of its interior lines to hold him back and punish any careless or ill-advised advance, being aided in this when possible by the fire of the heavy guns of the place. Care must be taken to avoid too great dispersion of the troops, and exposing advanced parties to being cut off and captured by pushing them too far to the front or holding their positions too long; but no opportunity should be missed of attacking and destroying or beating back hostile detachments when tactical conditions warrant it.
The defence during the first part of this period differs but little from the ordinary defence of an intrenched battle-field. The principal differences arise from the fact that the flanks of the advanced lines and the lines of retreat to the work are so well covered that with ordinary precautions they may be considered secure, and all energies may be directed to meeting the front attack and executing offensive returns. So soon as the point of attack selected by the enemy becomes known the advanced positions may be more fully manned and equipped; trenches with inconspicuous parapets, or preferably without any, may be made to cover the infantry, field-guns, and sometimes siege-guns on travelling carriages. These positions may be, as previously stated, 2500 to 3000 yards from the permanent works, and the intervals between them may be swept by the heavy guns of the latter.
If these positions can be so strongly held as to compel the besieger to attack them with his heavy guns, he will be compelled to establish his first artillery position at a very great distance—possibly 5000 to 6000 yards from the work. [At Belfort, 1870, positions of this kind were taken only after seventy-seven days of siege.]
As the advanced positions may be subject to the fire of the heaviest class of siege-guns, if any parapet is made it should be of the nature of a glacis of gentle slope and little command. Infantry trenches should be made narrow and deep as a protection against shells and shrapnel ([Pl. IX], Fig. 84), and gun-emplacements should be as small as practicable and almost entirely in excavation, for the same reason. Positions so prepared suffer very little from gun-fire, and will frequently require attack by systematic approaches.
An efficient outpost service must be maintained in front of these positions to prevent their being taken by surprise.
When but a limited number of troops are available for defence it is of course impossible to push out the advanced posts so far to the front. In all cases, however, they should be placed at the greatest practicable distance.
106. Opening of Artillery-fire by the Defence.—The artillery-fire of the defence should be opened upon the besieger’s batteries, etc., before they are ready for action, so that the ranges may be obtained and the tables of fire corrected without interference by the hostile fire. If this can be accomplished, the increased effect due to the accurate fire of the defence may more than counterbalance the numerical superiority of the attack, and result in preventing the completion of some of his batteries and in silencing others.
If, on the other hand, the attack anticipates the defence in obtaining the range, his superiority in numbers and accuracy will frequently necessitate abandoning some emplacements and mounting the guns in others, where they may be used in the later stages of the siege.
107. Defence during the Bombardment and Assault.—The amount of ammunition which can be profitably expended by the defence during the bombardment must be determined by the quantity on hand and the advisability of exposing by their fire the positions of the guns.
The infantry troops and the light guns are held under cover, ready to be moved forward to meet the assault if made. Special care will be taken to avoid being deceived by false attacks; and the assault, if made, will be met as previously described (par. 6).
If the attack is repulsed, an offensive return may be made by the general reserve, assisted, when necessary, by the local reserves of the front of attack; but the garrisons of the permanent works should not be withdrawn from them for this purpose, as it is always possible that they may be needed to protect the works and cover a retreat. If the assault succeeds, the defenders will retire to their positions in rear, from which the strongest possible fire will be directed upon the pursuing troops and upon the captured position to render its possession difficult or impossible. If the assailants are driven off, the position is immediately reoccupied by the defence.
108. Defence during the Second Period of the Siege.—The point of attack having been definitely determined by the preliminary steps of the attack in opening the parallels and establishing the batteries, the besieged will at once proceed to mount extra guns and reinforce the troops upon the threatened fronts. He will keep his outposts or sentinels during this and the subsequent periods as far to the front as possible, to prevent surprises and to keep out reconnoitring parties spies, etc., etc.
From observations previously established, he will locate at the earliest possible moment the batteries, etc., of the attack, and will prevent their completion and arming by the use of shells and case-shot charged with high explosives, fired from howitzers and mortars. He will use his long guns for counter-battering those of the besieger, and generally for direct fire upon exposed targets.
By taking the initiative he may frequently obtain the upper hand in the artillery duel, and possibly be able to prepare the way for strong sorties, and the destruction of the besieger’s works. In any case he must at this stage develop the full fire of his guns and work them to their maximum value.
If, however, the superiority of the artillery of the attack is pronounced, and it becomes impracticable to serve any battery advantageously, it will be better to dismount its guns and remount them in other positions, as indicated in the preceding paragraph (par. 106).
All efforts will be made to prevent the construction of the parallels and approaches, their positions being discovered by the use of the search and other lights, and the work upon them retarded by direct and curved fire. For the latter light rifled mortars promise to be very effective.[7]
The trenches connecting the detached and intermediate works will be strengthened, and counter-approaches will when practicable be driven out to afford positions for enfilading the approaches. The field and machine guns will be held in constant readiness for use, and will be brought into action at every favorable opportunity; but will be withdrawn and placed under cover previously prepared so soon as the fire upon them becomes too severe to be endured.
Meanwhile a new position in rear, with its flanks supported upon the adjacent detached works, will be selected and made ready for defence in case the front line is taken.
The general reserve will be used for offensive movements, which are made whenever favorable opportunities arise, particularly in making counter-attacks after unsuccessful assaults.
109. Defence during the Third Period.—The defence of the detached works of an intrenched camp during the Third Period will be conducted, so far as the general reserve is concerned, in very much the same manner as during the Second Period; but in the immediate defence of the detached work itself, owing to the close approach of the besieger, its character will change. The artillery except the field and machine guns will be silenced, and the latter will usually be only available for defending the ditches and for repelling assaults. Light guns will, however, be held in readiness for temporary use when practicable.
The outposts will of necessity be drawn in and replaced by a chain of sentinels along the parapets of the covered way or the main parapet, who will pick off the besiegers at every possible chance, and will be reinforced by the rest of the garrison when an assault is imminent. All flanking defences will be kept in as good condition as possible, and in readiness to prevent the crossing of the ditch, or to repulse an assault. Grenades and shells will be kept in readiness to roll into the ditch, the breaches will be obstructed and mined if practicable, counter-mines will be brought into play, and all other possible measures taken to retard the approach of the besieger to the breach and to repel his assaults. When, however, the work is reduced to such a state as to make its defence hopeless, it should not be held at the expense of great losses to the defence, unless the besieger’s works can be considerably delayed by doing so. When the position consists of an enceinte with ordinary outworks, the investment during the Third Period of the siege will be closer, the opportunities for using the general reserve will usually disappear, and its troops will be merged with those of the general defence.
When, in this case, the place is to be defended to the last, all measures will be taken for the defence of the breach; and after this is carried, for the final defence of the inner retrenchments or keeps.
The tactical handling of the garrison for this purpose is in accordance with the principles already laid down (par. 6, and Art of War, pars. 282-84.)
The sorties recommended during a siege are, when made by the general reserve and in large bodies, usually carried out by moving the troops from the collateral works upon the flanks of the besieger’s works. In the close attack, however, they may be made by small parties moving to the front from the nearest outpost or salient. The object in all cases is the same—to destroy the enemy’s works, delay his advance, and inflict upon him all possible loss.