Double Apron Barbed Wire
In very basic terms there are two types of common barbed wire entanglements: concertina and double apron. Concertina wire is the classic spiral wire arrangement. These were easy to carry around and quick to deploy.
Double apron wire took a bit more time to set up but was considerable more durable against enemy infantry and artillery.
There were several types of double apron commonly used, one was rather basic while the other was more complex with additional strands of wire being used. Pictured to the right is the more basic version with several horizontal wires fixed along several pickets. Diangonal braces were fixed from the tops of the pickets to add additional support to the wire fence. These diagonals were called aprons.