Coastal Antitank Obstacles, WWII Tactical and Technical Trends, No. 35, October 7, 1943 (Lone Sentry)

The following information concerns types of construction of concrete walls and other antitank obstacles in Holland, Belgium and France. Further details on this subject are contained in the publication, German Coastal Defences, issued as Special Series No. 15, 15 June 1943 by the Military Intelligence Division, War Department.

Walls are used to block streets and roads in coastal towns, as obstructions on approaches to key points, and on the outskirts of towns generally. Road blocks of this type, erected in line with the front elevation of existing buildings, will often form a continuous obstacle along the entire sea front of the town.

Details of the steel reinforcement of such walls have not been learned but it is suspected that it is very light and in some cases does not exist at all. Hooked bars often project from the top of the wall and may be used to support wire. To increase the effectiveness of walls as obstacles, ditches are often excavated or pits are dug and covered with planks, road metal or netting.

In areas where large quantities of stone are readily available from quarries, road blocks are often constructed of stone and not concrete.

V-shaped walls may be found across beach exits, especially on open beaches outside of towns. Gun emplacements or small pill boxes may be found at the point of the V, which is to the front--towards the sea.

Concrete walls have a minimum thickness of 6 feet but probably average 8 to 11 feet in thickness. Height varies from 6 feet to 8 feet, 6 inches.

When walls are gapped, the gap is usually sufficient for one vehicle to pass at a time. In one type the walls are built opposite one another from each side of the road, the gap being closed at will by girders, rails or gates which fit into sockets precast in the wall ends.

Another obstacle that may be encountered in the coastal districts of northwest Europe is a staggered type of double road block consisting essentially of a pair of walls or barricades built one behind the other and projecting from opposite sides of the road for a distance of one-half to two-thirds of the width of the road.

These double road blocks may be constructed of masonry or concrete, or they may be earth-filled timber barricades. Horizontal and vertical members of timber barricades are described as 10-12-inch diameter pine logs, the vertical members driven deep into the ground. The walls are strengthened by diagonal bracing. Apart from the presence of a passage through them, these barricades would form an effective obstacle against a frontal assault by medium tanks, though a heavy tank may cross and probably demolish them. Where these barricades are constructed in concrete it is fairly certain that they are not less than 6 feet thick. The average height has not been reported.

Concrete obstacles known as "Dragon's Teeth" are also used to block streets, exits from quays, and well defined beach exits, particularly where the level of the beach approximates the level of any road or track. This type of obstacle often consists of three or four staggered rows, 6 to 8 feet apart, the distance between the teeth in each row being 6 to 8 feet. The "Dragon's Teeth" probably average 2 feet, 8 inches to 3 feet in height. It is possible that the teeth are connected at their bases, from front to rear, by concrete beams to prevent overturning. No information is available of any steel reinforcements in the teeth.

Concrete cubes are used in the same way as "Dragon's Teeth" and are also found across hollows in dunes which might provide exits for vehicles. Cubes are used in rows, not always staggered. In dune country they are generally on a forward slope, near a crest. Where the pillars are rectangular, they measure about 3 feet on each side by 4 feet in height. Other obstacles of this type are about 4 by 4 feet in dimensions.

In addition to concrete and stone, steel is often used in the construction of beach and road obstacles.

Steel tetrahedra, pyramid-like, are made of steel rails or L-sections. They consist of 3 or 4 lengths of steel in the form of a cone, with the ends embedded in concrete and bolted at the top. When obstacles are made of L-sections, the upper ends appear to be specially cut and are welded together at the apex. There are two types, one which is 3 feet, 3 inches high with the ends bolted or welded, and the other type 4 feet, 6 inches high, bolted 3 feet, 3 inches above ground level with the ends projecting above the join.

Steel rails are occasionally placed vertically in 2 or 3 rows to form blocks across streets or well defined exits on open beaches. The rails project about 4 feet above ground level and are embedded in concrete.