a. Dragon's Teeth and Ditches

One of the common forms of tank obstacles employed by the Germans is the "Dragon's Teeth," which consists of rows of reinforced, tapered concrete pedestals, cast monolithically on a common base. The concrete blocks vary in height up to 6 feet, and they are designed to immobilize a tank by bellying it. Fields of these blocks, used on a vast scale in the German West Wall and now installed also on the European coast, usually consist of four to eight rows in front of prepared positions. They are usually laid in straight lines to simplify artillery registration on them. In front of each of these fields the Germans normally dig an antitank ditch, at least 10 feet wide and, in exceptional cases, up to 60 feet wide.

Antitank ditches have also been dug at the approaches to coastal roads and key positions, and it is not unusual to find two ditches spaced only a few feet apart. Normally, these ditches have passages to permit the flow of single-line traffic. The rear walls of these ditches are usually revetted with concrete, earth, or brick, and some of them have steel rails projecting from the top.

Around strongly defended ports will be found antitank ditches 20 to 40 feet wide and up to 3 miles in length. They are usually laid in a zigzag course. Ditches of this length are most common in The Netherlands, but they are also found to a lesser extent in Belgium and France. In the construction of such a ditch in The Hague, the Germans demolished a row of three-story houses, more than a mile long.

These ditches are usually protected by a thin belt of wire, and by gun emplacements and pillboxes sited to enfilade the zigzag course of the ditch. Where streams or other water sources are available, the ditches have a sluice arrangement to keep them partially filled with water, or to flood them in the face of an attack.

Antitank ditches installed in front of defensive positions are usually 9 to 12 feet wide and up to 8 feet deep.

When employed thus, they are sited as follows:

(1) The ditches completely surround fortified positions, and radio-direction and other radio installations. Usually there is a thin belt of barbed wire 10 to 20 yards in front of the ditch and a thicker belt about 50 yards to the rear of the ditch.

(2) The ditches are dug in front of fortified areas on beaches, behind beach wire, and at the foot of sand dunes.

(3) The ditches are dug in front of antitank walls and sea walls in coastal towns. They are usually without revetment, and may be dug 10 to 20 yards in front of the wall, or immediately in front of the wall.

b. Miscellaneous Obstacles

(1) Chevaux-de-frise.—Portable barriers of the cheval-de-frise type are commonly used by the Germans to block streets and important highway intersections. In some coastal places these obstacles are moved into position every night, evidently as a safeguard against commando raids. In other spots they are merely kept ready for placing during alerts. Two types of trestles for chevaux-de-frise are illustrated in figure 19.

Figure 19.—Types of steel cheval-de-frise trestles.

(2) Logs and rails.—Logs and steel rails of varying heights are employed for making fixed and movable obstacles. Usually they are laid in "asparagus beds," the individual rails being spaced about 4 feet apart. Angle-iron frames with upright steel rails, set in pairs on a common base, are also laid in rows to form barriers. The example shown in figure 20 is more than 6 feet high. Various kinds of "swinging gate" obstacles are used in large numbers to block streets.

Figure 20.—Angle-iron obstacle.

(3) Wire obstacles.—The Germans sometimes use concertina wire, disposed in depth, as a road block. (See also par. 10, above.) They are also apt to conceal antitank and antipersonnel mines in these obstacles.

c. Walls and Promenades

(1) Walls.—At many points along the western European coast the Germans have built concrete walls to serve as antitank and antipersonnel obstacles. Such walls usually are placed to obstruct the ends of thoroughfares and other easy exits from beaches and harbors, and to block the approaches to key positions back of the beaches. Their dimensions are from 6 to 8 feet in thickness, and up to 20 feet in height. In various places in Belgium the Germans have installed behind these walls several types of antitank barriers which were removed from the Belgian defense lines of 1940. Both stationary and portable flame-throwers may also be encountered at these barriers.

Walls installed across the full width of a street are 6 to 8 feet high and may be from 8 to 11 feet thick. They are reinforced with concrete bars, the ends of which protrude from the tops of the walls to serve as pickets for barbed wire. The backs of these walls are generally sloped and may have fire steps from which to operate antitank guns. Walls of these same dimensions are sometimes constructed in V shapes at beach exits, especially on open beaches outside town limits. The point of the V is toward the sea. Some wall obstacles blocking the ends of thoroughfares opening on beaches have gaps in them to permit the passage of a single vehicle at one time. These obstacles are of two types. In the first, a section of wall is built at each side of the road, and the gap between them is closed, when necessary, by steel rails, girders, or gates that fit into sockets of the walls. The other type also has two sections of wall, but these are not directly opposite each other. They are "en chicane," or staggered, one section being as much as 16 feet behind the other, on the opposite side of the road. This arrangement compels a vehicle to slow down and zigzag to pass through.

Long stretches of concrete antitank walls are built along the rear edges of beaches and across the estuaries of streams, with gaps to permit the flow of water. Where the regular sea walls are not very high above the level of the sand, they are sometimes adapted as antitank barriers by excavating accumulated sand drifts and gravel from their seaward bases, or by heightening them with concrete. In some cases there is an outward bulge below the top front edge of these walls to make them more difficult to negotiate.

(2) Promenades.—The promenades or boardwalks so common along the beaches of The Netherlands, Belgium, and France must also be considered as formidable obstacles, for infantry as well as for motor and armored vehicles. In many places they have been strengthened with reinforced concrete, and emplacements have been built into them. A typical example of such a promenade is shown in cross section in figure 21. (Other examples of the defensive use of promenades may be found in sec. IV, par. 17g and i, below). Figure 22 shows how concrete blocks are used to discourage tanks from negotiating the stairway leading from a beach to the walk of a promenade.

Figure 21.—Cross section of typical European beach promenade.

Figure 22.—Antitank obstacle at top of promenade steps.

d. Concealment and Deception

(1) Camouflage and concealment.—The Germans consider camouflage, concealment, and deception as very important and effective means of defense and have used these factors extensively in protecting coastal installations from ground as well as aerial observation. Troop shelters, pillboxes, hangars, dumps, and submarine and speedboat shelters have been constructed underground at all strategic points of the European coast. All open emplacements and the entrances of surface and underground installations have been skillfully disguised to add the protection of near-invisibility to the strength of reinforced concrete. The camouflage varies to blend with the different types of terrain in German-occupied countries.

Forms of camouflage and concealment that have been noted are as follows:

(a) Garnished nets, turf, and seaweed are used to conceal concrete bunkers in northwest France.

(b) Tanks, probably worn out or obsolete, have been buried in the sands of the coastal regions of France and Belgium, the gun turrets painted to blend with the sand. Private houses in the same area have been converted into gun emplacements without altering their external appearances.

(c) Some underground machine-gun nests are concealed by a natural earth covering about 3 feet thick.

(d) Certain large shelters capable of accommodating approximately 500 men each are camouflaged green, gray, and black. (This is a fairly common German camouflage combination.)

(e) Extensive use has been made of nets to camouflage harbor installations.

(f) In northern France props have been used to conceal surface hangars and airfields in order to make them look like a village from the air. On one airfield was installed a light wood framework, painted to look like the side of a farm house. A false top was painted to represent tiles. A number of other false buildings, including a replica of a church, were also installed in the same place.

(g) Numerous camouflaged shelters for individual planes are also reported. In one place they were built among trees at the edge of a wood. The shelters were of wood, with gabled roofs, were covered with netting, and had trees painted on the doors. In other places individual hangars take the form of farm buildings and hollow haystacks. Many shelters have been camouflaged to look like sand dunes or have been buried in dunes in areas with long, sandy stretches.

(h) In rocky country, the combination of camouflage around concrete forts is likely to consist of rocks and nets. In one region where the sand has a yellowish tinge, the Germans have camouflaged their installations with yellow patterns, broken by green stripes.

(i) Pillboxes and light-gun emplacements are concealed with heaps of the rubble caused by Allied bombings.

(2) Dummy installations.—The use of dummy works and weapons is extensive and serves the double purpose of distracting aerial observation from actual defenses and of inducing the enemy to make wasteful attacks on barren areas while the real defenses remain in operation. A common practice is to install dummy antiaircraft-gun positions and dummy guns, and even to simulate gun flashes in such positions, usually along lines of probable air approach. Sometimes real, mobile guns fire from the dummy positions in an effort to confound aerial reconnaissance. The practice is also extended to other types of artillery. Railway-gun turntables suspected of being faked have been noted in aerial reconnaissance. Dummy observation posts have also been reported. In some places that are heavily mined and wired but do not have a great many weapons, sham turrets and wooden guns are planted in barbed-wire lines.

Many dummy airfields exist along the coast of western Europe. Mock or disused planes and dummy buildings are installed on these fields, and at night they are likely to flash landing lights. From time to time the dummy aircraft are moved around to help fill out the impression of a field in actual operation.

Dummy installations are likely to be deliberately ostentatious or poorly camouflaged, in order to draw fire and distract attention from real and cleverly concealed fortifications.