Barbed Wire

"Used to slow down enemy infantry movement. Can be dismantled with a Wrench."

- In-game description

The player-constructed Barbed Wire drastically reduces both friendly and enemy infantry movement. It does not affect vehicles in any way. The only way to remove it is to dismantle it with a Wrench.

Placement
When placing barbed wire, it's important to remember that it hinders both friendly and enemy movement and should generally only be put in areas that the enemy will want to move through but your team will not. For example, you could place it on the far side of Sandbags to deny the enemy the ability to use it as cover from your direction of fire, or on the side of a building that enemies will want to take cover behind.

Common mistakes include placing it in the middle of roads behind the defensive line, where it is guaranteed to inconvenience only your own team until the battle is over, or placing it immediately in front of the defensive line, where it will prevent allied soldiers from advancing but will not prevent enemies from using anti-structure items, such as High Explosive Grenades, on them. Even placing a solid line of it outside HE grenade range may be detrimental in that it equally prevents your side from pushing forwards through that area.

Though it can easily be disputed that placing barbed wire in the middle of roads while having Sandbags on the side not blocking the main road will in a very minor way slow down your team while providing ample defense against enemy infantry. Though this type of defense placement is very vulnerable to vehicles due to it not blocking the road itself and Barbed Wire not blocking or slowing down any sort of vehicles. A simple Gun Turret behind this defensive placement will provide ample defense against the enemy while only mildly inconveniencing your own team due to them simply being able to hop over sandbags or go around. Enemy units now instead wont be running through no defense on roads.

(Metal) String Theory: The Assault Lane
Barbed wire is an obstacle to friend and foe alike, and due to this property it is the subject of mixed opinions. Defense-minded players appreciate its ability to block off alleyways and narrow gaps, to hinder movement through areas of concealment, or to force enemy attacks to run headlong into AI defenses or machine guns. Offense-minded players find it limiting to counter-attacking the enemy as it often blocks off the most direct route to the enemy. As lengthening the march to the enemy reduces offensive pressure, an impermeable wall of wire is undesirable.

Wire should be therefore be built as a means of controlling, not stopping, movement.

A barbed wire screen is a perimeter of wire on the enemy's likely or known axis of approach. Wire should, save for the "assault lane" mentioned below, be spaced tightly enough the enemy cannot pass through without almost certainly snagging the wire and being slowed. Ideally, wire screens keep the enemy out of range for throwing HE grenades at your foxholes and trenches. At night or in bath weather, vision is drastically reduced and a wire screen too far forward may be obscured. If the enemy can crawl through the wire undetected, it has created a false sense of security and may be worse than no wire at all.

Barbed wire screens must, with no exceptions, contain an obvious "assault lane" for friendly troops to use when retaking the offensive. Designating this lane with a signpost will help teach this concept. When possible, build the assault lane as the first element of the screen so it will always be clear while you work. These should be comfortably spaced for friendlies to pass through without scraping the wire yet still force the enemy to run headlong into direct fire with little space to evade. An example is section of wire missing from the screen and replaced by two wire sections forming a funnel away from one of your stronger firing positions. The gap should be clear of concealment on the friendly side to prevent the enemy's easy infiltration. Lane exits should never be under enemy fire, and should always be wider facing the enemy to give your forces more space to evade. Do not build zig-zags; they will frustrate friendly forces trying to leave and encourage the enemy to evade defensive fire.

The mark of a good assault lane is a pile of enemy backpacks at its mouth for the counterattack to admire. The mark of a bad assault lane is friendly backpacks at its exit, because it fed into an area the enemy could easily defend.

Barbed wire should be placed where the enemy will be under fire while attempting to dismantle it. AI foxholes are good for this purpose, as are garrison bunkers. In active sectors, trench lines and bunkers with firing ports can provide the most potential firepower of all, but only so long as the engagement lasts. Objects blocking vison, including the common sandbag/wire combination, create a weak point where the enemy can remove your wire and then seize the piece of cover.

To this end, tank traps and wire should not be built together. Wire is useful to separate aggressive tanks from their supporting infantry. Once beyond the wire, tank traps and mines are to keep tanks from crushing infantry trenches.

In urban areas, wire can be built to partially or completely block streets and alleyways with relative ease. Care should be taken that the approaches your side will use to enter a house remain open to your spawn points while the enemy has to pass through wire to reach their door. The idea of assault lanes can still be practiced with passable gaps to the enemy in places always kept under fire. Wire at an angle from a building corner can force the enemy to run into the middle of a crossroad and easily shot.