German Concentration of Fire--Medium Mortars, WWII Tactical and Technical Trends, No. 38, November 18, 1943 (Lone Sentry)

The article which follows deals with the possibilities for concentrating fire and is confined to an explanation of the simplest methods. The directive embodying these details is in the nature of a supplement to the German Army Manual 104. (H. Dv. 104) 1940. No new aiming and firing procedures are involved nor is additional laying and firing equipment required.

Attention is particularly directed to the possibility of bedding-in the base plate and to the terms "voice control action" and "position correction."

The German thought here shows the tendency towards concentration of supporting fire, and though it purports to be a supplement to the Manual of 1940, it does, in fact, it appears, represent a considerable change in policy.

An American unit in the field compares the supplement and the earlier Manual as follows: "The earlier Manual considers that medium mortars should normally be sub-allotted in pairs to forward companies, and even foresees occasions when single mortars may be placed under command of infantry platoons; the control of medium mortars by the mortar platoon commander and their concentration at battalion level is regarded as exceptional whereas in the later supplement all the emphasis is laid upon concentration as the normal policy. Recent fighting has demonstrated the effectiveness of the new policy."

Since mortars are likely to be among our most formidable enemy weapons in the future, this whole account should prove of interest.

Where an English equivalent exists but differs from a literal translation of the German, the English equivalent has been preferred. The terms "section" and "section commander" have been used to translate the German "Gruppe" and "Gruppenführer" and mean respectively a section consisting of two mortars, and the NCO in charge of such section.

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a. General

(1) Concentration of the fire of several mortars increases fire effect. The fire of one section, two sections or of a complete platoon may be concentrated, depending upon the tactical situation, the number of the targets, their nature, and the ground. When two sections or a complete platoon are engaged, the fire unit will be the section. The effectiveness of the concentration will be especially high if the target can be taken by surprise by a sudden hail of fire at maximum intensity.

(2) Platoon and section commanders must, therefore, continually strive to concentrate their fire on the most important targets not only at the beginning of an attack but throughout its duration. Should a number of targets appear at the same time it may then be more effective to silence them one after another by the concentrated fire of the section, than to engage them simultaneously each with a single mortar. The platoon or section commander must decide (guided by the nature of the target, its breadth and importance, and the demands of the situation, or of his own troops) how, and in what order targets are to be engaged.

(3) Concentration of fire may also prove very effective in defense when directed on enemy OPs, machine-gun nests, assembly areas in dead ground, woods, outskirts of villages and so on; it may be the deciding factor in the repulse of enemy attacks. Platoon or section commanders must take all measures within the framework of the fire plan to ensure that the fire of their mortars can be concentrated on the maximum number of points.

(4) Sound intercommunication is essential for rapid concentration of fire--in the case of a section, between the section commander and his mortars, and in the case of two sections or the whole platoon, between the platoon commander and the individual sections.

In the first case, transmission of orders by relayed voice or remote control procedure will normally suffice. The provision of a line link from the section commander's OP to the mortar position, or to the OP of the second mortar is only necessary where considerable distances are involved owing to the nature of the ground or enemy activity, and will be the exception.

On the other hand, when two sections or the complete platoon are engaged, a line link will frequently be necessary from the platoon commander's OP to the section OPs. The platoon commander will detail the sections providing signals apparatus, and decide whether the link is to be laid and maintained by platoon HQ orderlies or by section personnel.

(5) Rapid and unhesitating target indication makes for quick fire concentration, and increases the flexibility of the fire. A given target may be indicated by:

(a) Pointing out on the Ground

This method is the rule where a section is to engage. The section commander points the targets out personally to both detachment commanders in cases where he hands over fire control to them. Should he control a mortar himself, then in order to save time he will normally entrust the detachment commander of this mortar with the task of indicating targets to the other mortar.

When a complete platoon is in action, this method of target indication is only possible if the sections are close together. In general, the method is excessively lengthy, and as a result, the platoon commander will normally choose one of the following procedures according to the situation, and time available.

(b) Fire by the "voice control" section

In order to be able to control and, if necessary, concentrate the fire of several sections, or to bring the fire of one section quickly down onto a target, the platoon commander will site his OP within shouting distance of a section OP (i.e. the OP of the "voice control" section). Then, to indicate a target to the other sections, he orders the "voice control" section to fire on the target using one mortar. In this connection it should be noted that the element of surprise will be forfeited by the preliminary round. This method is therefore only to be recommended when engaging targets which cannot quickly move out of the fire (see paragraph 7 below).

The platoon commander names a number of conspicuous topographical features distributed in breadth and depth over the battlefield in the presence of the section commanders:

e.g. "right hand edge of wood", "haystack", "lone tree", "brown knoll". Any target appearing will then be described in relation to one of these reference points, or its distance in line from one of them given in terms of mils** measured by the binoculars:

e.g. "machine-gun right hand edge haystack", or, "OP 50 mils left of the lone tree". This method is quick, and will be found convenient where speed is necessary, as for instance in the case of an encounter attack or while an attack is still in progress.

(d) Target key

The target key takes the form of a simple field sketch or panorama, in which conspicuous points are indicated by a capital J and a number.*** The key is then distributed to sections. Indication of targets follows in accordance with paragraph 5 above. Fire orders will be determined and referred to in relation to individual J-points. The key must agree with the key in use by the unit to which the mortars are subordinated (company, battalion, etc.) This method takes time, and its use is, therefore, frequently confined to the deliberate attack and to defense.

(6) When fire is concentrated individual mortars will nonetheless be laid on the target or the allotted portion of the target area in accordance with the laying procedure given in Army Manual 104. Bunching and careless behavior during laying must be avoided.

(7) In order to retain the element of surprise when fire is concentrated, ranging will normally be carried out by a single mortar firing on a registration point (i.e. another target, or a feature in the vicinity of which the enemy is believed to be). This registration point must lie at approximately the same range as the target which is to be engaged, and should not differ from it in line by more than 300 mils.**** A range finder is considerable assistance when firing on the registration point. As long as all mortar platoons are not equipped with this instrument, the platoon commander must obtain one on loan from one of the MMG platoons. Measurement of large variations in line using the binoculars requires much practice and should be frequently exercised on training.

(8) The other mortar in the section accepts the established range to the target and corrects it for position correction. Position correction is the distance in meters measured along the line of fire by which the second mortar of a section is either forward or to the rear of the first one.

In the above sketch the line R-A is the position correction of the left mortar in relation to the right one. Should large switches be made, then the position correction alters, as shown by the line R-B. In this case it must be worked out afresh.

The mortar position NCO estimates, or if sufficient time is available, paces the position correction. In order to do this he moves prolongation of the line Z-R counting his steps, until he reaches a point at which the left mortar appears to be at right angles. He adds this distance (in meters) to the ordered range for the right mortar. For example, if the ordered range for the right mortar is 1,200 meters, and position correction for the left mortar 55 meters, then the order for the left mortar will be "left 1,260." Should the second mortar be sited forward of the first one, then position correction must be subtracted from the range.

(9) Fire for effect, will normally be proceeded with only after the mortar has registered. When engaging fleeting targets, parties of troops in dead ground, wooded areas, or targets of considerable size, then shooting-in may be dispensed with if the situation demands it. When concentrating fire on large targets surprise effect or the necessity for conserving ammunition may make it expedient to register or shoot-in only one of the mortars.

(10) Bedding-in the base plate will minimize the disadvantages which arise when shooting with mortars which have not registered.

The following directions will be complied with when bedding-in the base plate:

After the detachment commander has aligned the base plate in accordance with H.Dv. 104, he will mark its dimensions on the ground and have the bed dug out. Its forward edge should be dug to a spade's depth***** and the rear edge to half a spade's depth; this will produce a slope of 15 degrees (see sketch).

An additional depression will be made to correspond with the breech piece socket, and the rear edge of the base plate should be level with the surface before firing. The base plate will then be stamped in. Large stones, roots, etc., should be removed from the bed.

On loose, sandy soils with a grass or heather surface, the turf that has been removed should be used to make the bed.

If the ground is frozen or hard the bed should first be broken up in order to prevent bounce, which makes shooting-in more difficult, and puts a severe strain upon the mortar.

On stony ground the bed should be dug deeper than usual and made up with earth or clay.

The construction of the bed takes from 3 to 5 minutes.

(11) When firing mortars which have not shot-in one must be prepared for a considerable dispersion of the first rounds, which may possibly also involve some short ones. This method should accordingly only be used when one's own troops are not situated too close to the target which is being engaged.

b. Concentration of Fire within the Section

(12) When preparing to concentrate his fire, or when actually firing, the section commander may either entrust detachment commanders with fire control, or himself control it.

(13) He will adopt the first course if the mortar positions are far apart. In this case the section commander merely indicates the target to the detachment commanders (or the relevant portion of the target, if the target is large), lays down the registration point for each mortar, should this be necessary, and instructs detachment commanders to report to him when ranging is completed. The detachment commanders carry out ranging individually and the section commander helps them out with observation. As soon as ranging has finished, the detachment commanders switch onto the target line and report, e.g., "Right mortar ranging complete. Mortar aligned on target."

According to the situation, the section commander may order both mortars to carry on with fire for effect either immediately after ranging has finished, or on his order. The amount of ammunition expended during fire for effect will depend upon the nature of the target and the state of ammunition supplies.

Should ranging have been carried out on registration points which differed considerably in line from the target, then if the situation permits, line and range to the target may be confirmed by a few rounds before fire for effect begins.

(14) Should the section commander himself act as fire controller, then he may either range both mortars one after the other, or only one of them. In the latter case the detachment commander who has been detailed to assist the section commander will range the other mortar while registration is proceeding. The base plate of this latter mortar may be bedded-in if the ground permits (see paragraph 10 above).

The mortar position NCO determines the position correction for the mortar:

As soon as ranging has finished, the mortar position NCO applies the necessary position correction to the range, and passes the result to the second mortar. The section commander then proceeds with fire for effect in accordance with paragraph 13.

c. Concentration of fire of Two Sections or of a Complete Platoon

(15) The section is the fire unit even when the fire of several sections is being concentrated. The section establishes the necessary data and carries out the engagement of the target in accordance with the platoon commander's orders.

(16) If the fire of several sections is to be concentrated, the platoon commander will site his OP at a point from which he can obtain the maximum uninterrupted observation over the battlefield. He details the section which he proposes to have close at hand as voice control section, and arranges communication to the other sections. He makes suitable preparations for target indication, bearing in mind the time factor and the tactical situation (see paragraph 5 above).

(17) Concentration of the fire of the sections will be regulated both in space and time; regulation in space will be co-ordinated with the method of target indication and must be as simple as possible e.g., "right section right half of target, left section left half of target. Section commanders will distribute the fire of the individual mortars.

(18) Limitation in time may be necessary on tactical grounds or for technical reasons--for instance, when ranging. Normally ranging will be in accordance with paragraph 7, which makes it possible for the platoon commander to lay down the registration points for individual sections.

The tactical situation may demand that sections range gradually, and at varying intervals, in order to preserve the element of surprise. In this case the platoon commander will order the time at which each section is to range.

(19) As soon as ranging is reported complete, the platoon commander will order fire for effect. This will be carried out in accordance with paragraphs 12-14. Simultaneous opening of fire by all sections in the case of surprise fire may be produced on the commander's order. The order will be passed, as the situation demands, by line, or by the fire of the voice control section. It can also be arranged on a time basis. If fire has to be brought down on the target at a certain time, the time of flight must be borne in mind.

(20) The platoon commander will observe the general pattern of each section's fire and report it to the relevant section, e.g., "No. 1 section short", or "Left mortar No. 3 section shooting left 30 mils". The section commanders thereupon adjust their MPIs (main points of impact). The fact that the platoon commander is also observing does not, however, absolve section commanders of their duty of constantly watching their fire and making independent efforts to improve it.

(21) Concentration of the fire of several sections is facilitated if the mortar positions are sited as close together as the situation, task and ground permit. Under these circumstances, also, the section continues to be the fire unit. Ranging may occasionally be carried out by only a single mortar. In this case position correction must be applied to all the other mortars when firing for effect. However, should the mortars not have been shot-in, shooting-in may be omitted (see paragraphs 9-11).

*Translated from the German Manual "Richtlinien für die Feuerzusammenfassung mit s. Gr. Werfern" 8 February 1943.
**A Mil is 1/6400th part of a circle and at any range subtends a distance of approximately 1/1000th of that range. There are approximately 18 mils to one degree.
***The "J" indicates an infantry (German-Infanterie) target. German practice is to number targets from the right, using numbers from the block 100-199 for battalion support weapon targets, e.g. MMGs and mortars; and from the block 200-299 for regimental support weapons, e.g. infantry guns. German artillery proper adopts a similar system except that numbers are used without the letter prefix. Note: It is to be observed that originally the Roman J was a Gothic I (see H. Dv. 139/9, paragraphs 91, 92) derived from Infanterie, and may still be found in some documents.
****i.e. about 17 degrees.
*****German entrenching tool is 8 1/2 inches long.