Railway Artillery - Operations
Railway Artillery seems not to have been recognized as an important and separate subdivision of Artillery before the outbreak of the Great War, 1914-1918. For this reason the idea and the material are thought of as new developments, whereas in fact both appeared almost simultaneously with the widespread adoption of railway transportation.
In considering the scope of utility of railway artillery in land warfare, several general limitations should be borne in mind. It is the heaviest, most powerful, and most costly of all artillery and for this reason, it should be exposed to a minimum of danger of destruction and capture, and should be used only when heavy mobile artillery will not suffice. It is hence used only for offensive operations and special service, being organized as a separate reserve and not attached to any one army. Except in sectors of a front, which have been quiet for a long while, standard gauge railway lines can not easily be maintained closer than from 5 to 10 kilometers to the line, hence heavy railway artillery can not be operated closer to the line. Further, experience has taught that it should be kept out of the range of the field guns and smaller caliber heavy guns. In some cases, as in the American St. Mihiel offensive of September, 1918, the railway artillery was run up to within 3 kilometers of the front lines.
Fire of destruction as executed by railway artillery has for objectives in general order of range:
- Permanently fortified works, as concrete turrets, observation posts, sentry towers or observation posts, concrete rampart shelters, concrete cantonment shelters, gun casemates, flanking casemates, and flank trenches, con- crete conmiunication galleries, troop shelters, machine gun and antitank forts.
- Bridges, culverts, cuts, and fills.
- Balloons and towers used for observation and located at long range.
- Centers of supply and distribution, as railroad yards, supply depots, ammunition dumps, industrial centers, etc.
Except in the case of Balloons and towers, it is obvious that, for the purpose of destruction the maximum plunging fire is desirable and that the pieces that should be used are howitzers and mortars, so long as the necessary range can be obtained with them. Centers of supply and distribution were ordinarily located at such ranges that guns must be used, It is evident that relatively large explosive charges and perhaps numerous shots will be required for this purpose and, except in the last case, very high accuracy of fire is essential.
Under the heading of counter-battery work is ordinarily included the destruction of only such enemy batteries as are so distant as to be beyond the range, or so well protected as to be beyond the destructive power of the army artillery. Occasionally it may be imperative that certain batteries be put out of action in much less time than would be possible with army artillery that must be moved up from some other locality. In these cases, obviously, railway artillery capable of aU-roimd fire should be used. Circumstances demand ordinarily cannon of long range and medium caliber for this work and mounts provided with facilities for the most rapid and universal service: This would include mounts whose firing platform requires a very small time for installation, and mounts provided with traverse for all-round or nearly all-round fire.
The objectives of fire of interdiction are lines of communication, roads, railroads, telegraph, and telephone lines, etc. It may be very desirable to keep a section of a certain railway line out of commission. It may be desirable likewise to shell certain sections of very important roads over which supplies and men must be moved. At night a few shells per hour may be sufficient to seriously interrupt traffic. During the day when observation is possible more active shelling may be carried out. Guns of long range, medium caliber, and large traverse are preferred for this work. The practice has been to carry out fire of interdiction only when it will be most effective, i. e., immediately before, during, or immediately after, an attack.
The objectives of bombardment for moral effect are large centers of population long distances behind the lines. The aim is to destroy any sense of security which the distance from the front lines may give the civilian, to undermine the spirit of the army by weakening the morale of the civil population, and to interfere to the maximum with the administration of the war. The characteristic of first importance for this kind of fire is extremely long range, 100 to 120 kilometers or so. Difficulties of construction seem to limit the caliber of these long guns to about 240 millimeters. Little or no traverse is required. At least one shot per hour is considered necessary to produce the desired effect, and absolute regularity in the bombardment is necessary for the maximum effect on morale. The single example of action from a gun of this sort was the bombardment of Paris.
Railway artillery is far too difficult to manufacture and too valuable to be used except at the nearest possible approach to a 100 per cent efficiency basis. It would be most unwise to undertake to destroy certain heavy concrete fortifications with 194-millimeter howitzers, involving the expenditure of a great amount of ammu- nition and considerable wear of the guns and perhaps, after all, not accomplishing satisfactory results, when a few shells from a 320-millimeter howitzer would accomplish the desired results. Further, it would be criminal to use 320-millimeter howitzers on machine-gun forts, sentry towers, etc., if smaller howitzers were available.
In the region northeast of Soissons the Germans were using in 1917 some old quarries very similar to a series of mine galleries, some 90 feet or more under ground, as troop shelters. The French were aware of this fact, and in preparing for their offensive in this region, decided to attempt the destruction of these shelters. 400-millimeter howitzers were assigned to the work, and with their great weight of projectile, high angle of fire, and consequent nearly vertical drop of projectile, accomplished very satisfactory results. The shells penetrated the overlying earth and chalk to a depth of about 50 feet and on bursting caused great sections* of the roofs of the galleries to drop, imprisoning or killing the Germans.
As with resistance of target so with range, no more powerful gun should be employed than is absolutely necessary. Wear, first cost, and time of manufacture are all much less on the shorter and less powerful guns. The following table, which is taken from French experience, shows clearly the relative rates of wear at the various ranges. It is evident that to use a 300-round gun on objectives that could be de- stroyed as effectively by from 2,000 to 4,000 round howitzers would be nothing short of criminal.
In regard to the other two points, cost and time of manufacture, only about half the time is required to manufacture a howitzer as to make a gun of the same caliber, lighter machinery may be employed, and the cost is even less than half. The accuracy life of any gun is greatly increased if it is fired with reduced charges and consequently reduced muzzle velocities.
In view of these facts it would seem best to use the shortest gun and the lowest charge and muzzle velocity possible. The closest point at which it is possible safely to locate the piece determines, of course, the range. Ideal practice, therefore, would be to use the shortest piece of the required caliber, which at its most favorable elevation can realize this range. If the nearest piece to the ideal which is available has a range materially greater than that required, then it should be fired with as much of a reduced charge as possible.
In this connection it is, of course, understood that the designer and builder and the users of the gun will probably never agree on the question of their proper use. A prime and proper desire always in the mind of the user is for greater and greater range. The designer and builder dislikes to see his machine abused and wishes to keep the muzzle velocity as low as possible.
For counter-battery work it is ordinarily necessary to move the guns up and prepare them for action in a minimum of time, this minimum being counted in hours (six or less). It is desirable, like-wise, that it be possible to remove these mounts within a half hour or less. In such cases, which are really emergency cases, the mounts affording wide traverse or all-round fire and requiring not more than an hour for emplacement will be chosen.
Ordinarily, arrangements for the use of railway artillery may be made very deliberately. If there is plenty of time, the necessity for the use of a cumbersome firing platform may not be a handicap. There is no objection to having the men do the manual labor of putting down a platform since, ordinarily, the battery commander may be hard put to find enough work to keep his men busy and contented.
Developments during the Great War considerably changed conditions. All along the line it has become possible to moount heavier artillery on mobile carriages and therefore the line marking the upper limit of heavy artillery has advanced, restricting the field of railway artillery. The upper limit of railway artillery in respect to range is also fixed by economic rather than by physical limitations. Guns of extreme range used in distance bombardment for moral effect can perfectly well be mounted on railway carriages, but their utility as compared with bombing planes is a mooted question. Indeed it may be questioned if such planes will not supplant artillery even at shorter ranges.
The dispersion of the United States 14-inch, 50-caliber gun at the extreme range of about 40 kilometers is about 4 kilometers. It fires a shell carrying about 40 kilograms of explosive and has a life of perhaps 300 rounds. This gives a total of 12,000 kilograms of explosive placed somewhere in an area of 16 square kilometers during the life of the gun. Twenty-five heavy bombing planes could drop this amount of explosive in a single raid, and, even at night, ought to be able to put it inside an area so large as 16 square kilometers.
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