German Railway Flak, WWII Tactical and Technical Trends, No. 17, January 28, 1943 (Lone Sentry)

Protection of troop and freight trains is determined by such weapon disposal as best assures the safe arrival of the train with the minimum of losses. The following article, reproduced by permission of the British Air Ministry, contains information which supplements that reported in Tactical and Technical Trends, No. 5, p. 7.

a. Equipment for Defense of Trains

The normal Flak gun for the defense of trains is the 20-mm; machine guns are also used. It is possible that the 37-mm gun may sometimes be used, though this is not known for certain. The accompanying sketch shows a 20-mm railway Flak detachment.

[German 20-mm Antiaircraft Gun]

An open freight car is the type commonly used for the 20-mm gun according to the German manual. The gun can be accommodated at one end, and the crew under a removable roof at the other; alternate positions are provided at either end of the car so that the gun position and crew shelter can be reversed, if necessary.

The muzzle-brake is removed from the 20-mm gun to reduce the length of the barrel. Safety fences on all four sides of the gun insure that it is not fired below the safety angle. These measures make it impossible for the gun to strike obstructions such as tunnels, signal posts, or other trains. Other safety measures include the posting of look-outs to prevent firing which might damage telegraph wires, signal posts, tunnels, or other obstructions, and a complete prohibition of firing on electrified lines with overhead cables.

Photographic evidence suggests that, in practice, converted passenger coaches and roofed freight cars with part of the roof removed are often used instead of freight cars--a measure probably dictated by the need to economize in specially constructed cars.

b. Employment

It is understood that the allotment of Flak cars per train is as follows:

(1) Three cars mounted with machine guns placed a quarter, a half, and three-quarters of the way along the train.

(2) Three cars carrying 20-mm light Flak guns: one in the middle of the train, one at the rear, and one immediately behind the locomotive. The gun behind the locomotive is not manned, being a spare to permit reversing the train without shunting the guns.

(3) On especially important trains an additional 20-mm gun is carried on a car in front of the locomotive.

In practice the allotment of Flak cars varies considerably, and it is probable that the full allotment is rarely allowed. A recent report stated that on French railroads two Flak cars, instead of the usual allotment of one, were to be run at the rear of all trains in use by the armed forces; on the other hand, in many cases an allotment of as little as one gun to a train is made.

Examples of trains (believed to be military) photographed in France are as follows:

(1) Engine, 5 passenger coaches, 5 box-cars, Flak car, 12 box-cars, 5 flat cars, 3 box-cars, 8 flat cars;

(2) Engine, 4 passenger coaches, 14 flat cars, Flak car, 25 box-cars;

(3) Engine, 23 flat cars, 5 box-cars, Flak car, 3 passenger coaches, 2 box-cars, 16 flat cars, 1 open car, 2 flat cars, and 1 box-car.

It is of interest that, in most cases in these examples, the Flak car is preceded or followed by box-cars, which must presumably hinder somewhat the field of fire.

On the move the guns, continuously manned, are allotted 180° priority arcs as follows:

(1) Forward--the front MG and center 20-mm guns;

(2) Rearward--the center and rear MG's and the rear 20-mm gun;

(3) Forward--the 20-mm gun in front of the locomotive (when carried).

When the train is stopped, the guns may be moved from the cars and deployed on the ground so as to give a better field of fire. The decision to do this naturally depends on the probable length of the halt.

c. Protection of Ground Areas and Lines of Communication

In many parts of Germany and also, it is believed, elsewhere (especially in Russia), mobile heavy and light Flak units are employed with guns on railway mounts. They may be equipped with any of the following calibers: 20-mm (single or four-barrelled), 37-mm, 75-mm, probably 88-mm, 105-mm, and possibly 150-mm. These units move from place to place in special Flak trains, with their own living and kitchen accommodations. The heavy guns are not fired on the move, though no doubt one or two of the light guns are manned for defense of the train. On arrival at their destination the trains are broken up, and the guns and equipment sited on sidings.

Considerable reliance is placed by the Germans on these railway Flak units as a means of providing rapid reinforcement to threatened areas. Air reconnaissance has shown that frequently railway Flak has been moved to ground defense areas after a heavy RAF attack, in the expectation of further attacks on subsequent nights. Instances have also been reported of the employment of railway Flak at objectives where, for reasons of expediency, no permanent Flak protection is provided.

Apart from the reinforcement of ground defense areas, railway Flak units are used, especially in theaters of active operations, for mobile protection of railway communications. For this purpose light guns are apparently considered of most value, presumably since stations, junctions, loading bays, and sidings are particularly vulnerable to low-flying attack.

d. Composition

Heavy railway Flak units identified from air photographs normally consist of four heavy Flak cars, two light Flak cars, and a command group. The command group comprises cars of a special type, often four in number, one of which carries the Kommandogerät (director and rangefinder) and a second, in some cases, equipment for remote fire control. The purpose of the remaining two cars is not entirely clear; one is possibly a plotting and control unit for the use of the gun position officer (battery executive) and the other may in some instances carry a searchlight. In many instances the command group is confined to two cars. These may correspond with the first two cars of the four-car command group, though it is not unlikely that they may be associated with units equipped with the lighter auxiliary fire-control instruments only, one car carrying the auxiliary director and the other the rangefinder. In addition to the operational cars there are several coaches which provide accommodation for the personnel.

e. Siting

So far as the limitations imposed by the railway tracks permit, an effort is made to lay out the gun positions in the normal manner. The heavy Flak cars are usually sited on the unoccupied tracks of a siding at the corners of a rectangle, the long sides of which generally vary from about 40 to 80 yards. The command group is sited at one end of the position, some 100 to 300 yards distant, and the light Flak cars generally at either end of the position. A position of this type is shown in the sketch on the following page.

[Railway Gun Siting]

When only a single siding is available, the heavy Flak cars are sited along it at intervals of 40 to 50 yards, the remainder of the position being similar to the type described above.

f. Construction

There appear to be two main types of heavy and one main type of light Flak cars. Their dimensions and construction are shown in the accompanying sketches; since the measurements are obtained solely from photographic interpretation, they are subject to a margin of error of 10 to 15 percent.

[German Light and Heavy Flak Cars]

The extension to the center part of the broad-type heavy Flak car (outside the dotted lines in the sketch) is clearly shown by photographic evidence to be a folding flap. It is highly probable that the platform surrounding the raised portions is also capable of being folded or detached when in transit, since the movement of a 15-foot vehicle would be impracticable, except possibly on special sections of a railroad. The raised portions are about 2 to 3 feet above floor level; it is of interest that, whereas they are surrounded by a platform in the broad-type car, they extend the whole width of the narrow type.

g. Organization

Railway Flak units are organized into regiments, battalions, and batteries; the precise composition of the units is not known. It is believed that the regimental organization forms a pool from which units may be drawn as the necessity arises, either for mobile defense or for train protection. The unit most frequently met with is the battery, which in mobile defense probably moves and operates as a unit; in the case of train protection, the battery headquarters presumably administers detachments allocated to different trains. Although railway Flak units are part of the German Air Force and are administered through the usual GAF channels, it is probable that train protection detachments are operationally subordinate to the transport authorities; there is some evidence that guns provided for the protection of military trains may in certain circumstances be manned by army personnel.