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 steel pickets, it is used to form military wire obstacles

Origins

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.

More elaborate and formidable obstructions could be formed with multiple lines of stakes connected with a wire running from side-to-side, back-to-front, and diagonally in every possible direction. Effective as these obstacles were, their construction took considerable time.

Barbed wire obstacles were vulnerable to being pushed about by artillery shells; in World War I, this frequently resulted in a mass of randomly entangled wires that could be even more daunting than a carefully constructed obstacle. Learning this lesson, World War I soldiers would deploy barbed wire in so-called concertinas that were relatively loose. Barbed wire concertinas could be pre-prepared in the trenches-and then deployed in no-man’s-land relatively quickly under cover of darkness.

There was what might be called a concertina craze on: innumerable coils of barbed wire were converted into concertinas by the simple process of winding them round and round seven upright stakes in the ground; every new lap of wire was fastened to the one below it at every other stake by a twist of plain wire; the result, when you came to the end of a coil and lifted the whole up off the stakes was heavy ring of barbed wire that concertinaed out into ten-yard lengths.

Concertina wire packs flat for ease of transport and can then be deployed as an obstacle much more quickly than ordinary barbed wire

A platoon of soldiers can deploy a single concertina fence at a rate of about a kilometer per hour. Such an obstacle is not very effective by itself, and concertinas are normally built up into more elaborate patterns as time permits.

Today, concertina wire is factory made and is available in forms that can be deployed very rapidly from the back of a vehicle or trailer.

Dannert wire

The oil-tempered barbed wire was developed during World War I; it was much harder to cut than ordinary barbed 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 50 feet (15 m) long and each coil could be held in place with just three staples hammered into the ground.

The dinner wire was imported into Britain from Germany before World War II. the demand for Dannert wire was so great that some were 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 tickets 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 was 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 50 yards (46 m) of triple concertina fence in just 15 minutes. Optionally, triple concertina fence could be strengthened with uprights, but this increases the construction time significantly.

“Constantine” wire

Concertina wire is sometimes mistakenly called “Constantine” wire. “Constantine” probably came from a corruption/misunderstanding of “Concertina” and led to confusion with the Roman Emperor Constantine. This, in turn, has led to some people trying to differentiate between concertina wire and “Constantine” wire by assigning the term “Constantine wire” to what is commonly known as razor wire. In contrast to the double-helical construction of concertina wire, as shown being deployed by airmen in the image, razor wire, or less commonly “Constantine wire”, consists of a single wire with projecting teeth periodically along its length.

Sources – Wikipedia