right|250px|thumb|Triple concertina wire fence
thumb|250x250px|Baled concertina wire prior to deployment
Concertina wire or Dannert wire is a type of barbed wire or razor wire that is formed in large coils which can be expanded like a concertina. In conjunction with plain barbed wire (and/or razor wire/tape) and steel pickets, it is most often used to form military-style wire obstacles. It is also used in non-military settings, such as when used in prison barriers, detention camps, riot control, or at international borders.
During World War I, soldiers manufactured concertina wire themselves, using ordinary barbed wire. Today, it is factory made.
Origins
right|thumb|A sketch of a typical concertina wire obstacle
thumb|Concertina wire can be a feature of prisons.
In World War I, barbed wire obstacles were made by stretching lengths of barbed wire between stakes of wood or iron. At its simplest, such a barrier would resemble a fence as might be used for agricultural purposes. The double apron fence comprised a line of pickets with wires running diagonally down to points on the ground either side of the fence. Horizontal wires were attached to these diagonals.
Dannert wire
Oil-tempered barbed wire was developed during World War I; it was much harder to cut than ordinary barbed wire. During the 1930s, German Horst Dannert developed concertina wire of this high-grade steel wire. The result was entirely self-supporting; it did not require any vertical posts. An individual Dannert wire concertina could be compressed into a compact coil that could be carried by one man and then stretched out along its axis to make a barrier long and each coil could be held in place with just three staples hammered into the ground.
Dannert wire was imported into Britain from Germany before World War II. During the invasion crisis of 1940–1941, the demand for Dannert wire was so great that some was produced with low manganese steel wire which was easier to cut. This material was known as "Yellow Dannert" after the identifying yellow paint on the concertina handles. To compensate for the reduced effectiveness of Yellow Dannert, an extra supply of pickets were issued in lieu of screw pickets.
Triple concertina wire
A barrier known as a triple concertina wire fence consists of two parallel concertinas joined by twists of wire and topped by a third concertina similarly attached. The result is an extremely effective barrier with many of the desirable properties of a random entanglement. A triple concertina fence could be deployed very quickly: it is possible for a party of five men to deploy of triple concertina fence in just 15 minutes. Optionally, triple concertina fence could be strengthened with uprights, but this increases the construction time significantly.
See also
- Slinky