Armies use obstacles to influence the enemy’s actions on the battlefield. They can be used to delay, divert, turn, or channelize a force into the ground of your own choosing. What they very rarely can do is actually stop an enemy.
Some typical military obstacles include minefields, anti-tank ditches, and of course, wire obstacles such as barbed wire and concertina wire.
The normal emplacement of concertina wire is what’s called the “triple strand” where to rolls side by side on the ground are topped by a third roll above.
The triple strand obstacle is just a touch too tall for someone to jump over, and the barbs of the concertina wire make it virtually impossible to clamber over. It’s hard to see in the above figure, but the rolls are held in place by stakes on alternating sides of the obstacle every 6 paces.
By itself, a triple strand obstacle isn’t that hard to breach. It can be manually breached with wirecutters. It can be mechanically breached by using a grappling hook and a cable pulled by a vehicle to rip it out. It can be explosively breached by Bangalore Torpedoes or the MCLIC or APOBS.
Of course, your enemy won’t make it that easy for you. It’s a military truism that if you’re not observing your obstacle, it’s not an obstacle. Instead, most obstacles, particularly those used to channelize, are carefully crafted kill zones, with preplanned mortar and artillery fires, interlocking machine gun, cannon and missile fires from protected positions. You might be able to breach the obstacle, but you’ll pay a price.
Furthermore, you’ll rarely come across just a triple strand concertina obstacle. Usually they are employed in conjunction with an anti-tank ditch (on the mechanized battlefield, at any rate) and depending on circumstances, a minefield as well. Each of these obstacles requires a different breaching method, which increases the time needed to breach, leaving you in a kill zone that much longer. Further, once you have breached, your follow on forces are forced into a narrow channel that makes an excellent shooting gallery.
Of course, sometimes, the enemy doesn’t have the time or material to emplace a fully integrated obstacle. You might get lucky and actually come across just a concertina obstacle.
In that case, if you’re mounted in a Bradley or a tank, you can just drive through it. But that tends to have its own drawbacks.
Been there, done that, and it is a flaming pain to get every single bit out of the running gear.