Lone Sentry: Barbed-Wire Obstacles, German (WWII U.S. Intelligence Bulletin, September 1943)

1. GENERAL

With the German Army increasingly on the defensive, it is pertinent for us to know as much as possible about the enemy's employment of barbed-wire obstacles in continental Europe. A classic asset of the defense, barbed wire naturally plays an important part in the coastal and inland defense systems that the Germans are hurrying to complete in the occupied countries. The following aspects of German wire technique have recently been observed in France, The Netherlands, and Belgium.

On beaches, barbed wire is usually erected in straight lines, parallel to the shore and in front of fortified areas. Between these fortified areas, the lines of wire jut out at right angles toward the sea.

Around emplacements and fortified areas, the depth of wire obstacles varies, depending on the nature of the terrain and the importance that the Germans attach to the site. In some places the depth may range from 30 to 60 yards; in other positions, it may range from 70 to 130 yards, or may be as much as 200 yards. As a rule, the distance between the outside edge of the wire and the nearest pillbox or other firing position is at least 30 yards.

In gullies and in the crevices of cliffs, if ascent is considered at all possible, the Germans install dense wire entanglements. In front of these, the enemy sometimes places small-mesh wire, evidently for the purpose of slowing any advance in which Bangalore torpedoes might be used. Halfway up the gullies and crevices, the entanglements usually begin to thin out. Sometimes they continue as single fences running along the tops of the cliffs, near the margins.

In conjunction with road blocks, a wire fence or entanglement is often erected on each side of the road, and the gap between is closed by movable gates of various types. In many places concrete walls and other more substantial types of barriers are replacing wire entanglements as road blocks; however, wire is nearly always used on top of these wall barriers, for additional protection. Wall barriers and concrete emplacements are likely to have iron staples in them so that wire entanglements can be firmly secured.

Often the Germans use wire to fence off all sides of a minefield. Such fences consist of a single row of pickets connected by five or six strands of wire. Also, a thin belt of wire is commonly found outside antitank ditches.

The Germans are now making extensive use of a new type of barbed wire. This new type is made of a non-corrosive metal, and is thicker than ordinary wire. It is square in cross-section, rather than round. The wire, which is twisted, has 3/4-inch barbs, 4 inches apart.

2. SPECIFIC TYPES

The following are specific types of wire obstacles that the Germans are erecting in France, Belgium, and The Netherlands. Several of these types were encountered in North Africa, and any or all must be expected wherever the Germans have had an opportunity to prepare defenses. The dimensions given here an approximate.

a. Knife Rests

X-shaped metal knife rests, or "chevaux-de-frise," strung with wire, have been observed above the high water mark on beaches. Sometimes this type of obstacle consists of four trestles connected by a crossbar, and has the following dimensions:

Height 4 feet

Span of trestle legs 4 feet

Distance between trestles 4 to 5 feet

Length of four-trestle unit 16 to 20 feet

b. Apron Fences

These may be single or double aprons. They are supported by screw pickets or by angle irons embedded in concrete to a depth of about 18 inches. Often a coil of concertina wire is placed under a double apron fence, and sometimes another coil is placed along the top. The dimensions of a typical apron fence are as follows:

Height 4 to 5 feet

Height (with coil on top) 7 to 8 feet

Width Up to 30 feet

c. Vertical Fences

Ordinary vertical fences are always installed in two or three lines, from 4 to 8 feet apart. Each fence has five or six strands of wire, and is 4 to 6 feet high. The wire is supported by wooden posts, angle irons, or screw pickets. The spaces between fences are frequently filled with wire entanglements and mines.

d. Concertina Fences

Single, double, or triple coils of concertina, supported by angle irons or screw pickets, are often used as fences. Triple coils are frequently affixed to the protecting rails of the beach promenades which are so common in the coastal towns of western Europe.

e. Trip Fences

Trip wires are often laid in front of important beach obstacles. These wires will usually be found between the high-water mark and the first barbed-wire entanglement. They are also used in the minefields in front of main defensive positions and main obstacles. Trip fences have the following dimensions:

Height 4 to 6 in

Length of each diagonal or diamond-shaped section 4 to 6 ft

Width of whole obstacle 12 to 20 ft

f. Alarm Wires

The Germans often place some form of alarm device in barbed-wire fences. Grenades and small explosive charges are common. Insulated live wire, which rings a bell as soon as it is cut, has also been encountered. It must be remembered that almost any kind of improvised alarm device will serve the defenders' purpose, provided that it produces enough noise to warn effectively.

g. Electrified Wire

Electrified barbed wire, attached to pickets by means of insulators, has been reported. This type of obstacle is not used on a very large scale, however.

h. Combined Fences

A typical combined fence consists of the following units, in sequence: a trip wire, a trestle fence or knife rest, and an apron fence. The apron fence is likely to be from 10 to 20 yards behind the trestle fence or knife rest, and the total depth of the whole combination may be from 30 to 60 yards. On the sea fronts of towns, the Germans usually erect an apron or knife-rest fence on the beach, and a concertina or apron fence on top of the sea (retaining) wall or beach promenade.

3. STANDARD TECHNIQUE

The Intelligence Bulletin distinguishes between German technique which has actually been observed, and that which is prescribed in German training documents. Some notes regarding the latter are given below.

a. Obstacle in Depth

This type of obstacle is constructed to a depth of about 33 feet. It consists of ordinary wire fences erected at intervals of about 5 feet and connected with crisscrossed plain wire (see fig. 1). The spaces between the fences are filled with barbed wire in spirals. These spirals are fastened to each other and to the pickets of the crisscrossed wire. When obstacles of this type are erected in woods, trees are often used to support the wire.

[Figure 1. - German Barbed-Wire Obstacle in Depth. (WWII)]

Figure 1.—German Obstacle in Depth.

Wire obstacles in depth are usually installed in places where they will be screened as far as possible against observation by opposing forces. Woods, hollows, sunken roads, and heavily overgrown reverse slopes are sites especially favored by the enemy.

b. Wire-netting Fences

The Germans use wire netting as an emergency obstacle against infantry. They believe it to be most effective in woods and on the near side of hedges, and recommend that it be secured to the ground with wire and pickets. An obstacle of this type illustrated in a German training manual is 6 feet 6 inches high.

c. Trip-wire Obstacles

German training doctrine prescribes that these obstacles be at least 30 feet in depth. Irregular rows of wooden pickets, 2 feet high and 3 inches in diameter, are driven into the ground, and barbed or plain wire is stretched between pickets, at a height of 4 feet 8 inches. The interval between pickets in a row is 10 to 13 feet, and the interval between rows is 7 to 10 feet. Freshly cut pickets are painted to blend with the surroundings.

Trip-wire obstacles can be concealed effectively in gullies and on ground covered by low growth, especially if rusted wire is used. Mines and booby traps, equipped with pull-igniters, may be combined with these obstacles.