Defense: Obstacles Part IX: Reinforcing Existing Fences

In the last entry we examined a few different types of common wire and concertina wire.  In this entry we’ll take a look at ways of reinforcing existing fences to make them better obstacles.  Your average fence that exists now is probably suited for a specific task.  That task may be keeping livestock in, marking your property boundary, keeping feral animals out, etc.  Often by just adding a few more features to an existing fence we can create a viable obstacle that will help us to achieve a desired effect.  Remember from the last entry wire serves a lot of different purpose when it comes to defense.  Regardless of the purpose fence obstacles all have one thing in common: they are a pain in the ass for humans (and vehicles) to deal with but they are not the one stop absolutely don’t let anything in solution.  That solution doesn’t exist – but when it comes to the basic principles of obstacles wire is good – damn good.  This isn’t a primer that’s going to tell you what a widowmaker is, how far to space your t-posts or drive them in, what type of barbwire to use, or how to use fencing pliers.  There’s a gajillion sites on the net that gives that kind of basic info (there’s a good link at the bottom of this entry for it).

The most common type of fence you’ll see in rural areas is the steel T-post and barbwire fence.  There’s so many schools of thought on how to put these up (tight wire, slack wire, post spacing/depth, etc.) that it’d be pretty hard to address them all here so I’m going to highlight their common properties.  These fences normally consist of four or five stands of wire connect to standard t-posts at a fairly uniform interval.  The pic below illustrates a pretty common type:

Fences like these are pretty good at controlling livestock but suck at deterring humans.  Given that fact we’ll start off with some basic reinforcing and work our way up in complexity.  Complexity is a term you’ll see me use a lot when talking about wire obstacles.  There’s a rule I frequently use when discussing obstacles and that’s The more complex an obstacle the longer it’ll take the threat to a) figure it out, b) deal with it, and c) be more likely to deter a threat from taking that approach or route.  If you have a complex obstacle and the threat is unable to examine it from cover while you have good observation and fire on it then the threat is going to have a helluva time breaching it. After all – running up on a complex obstacle you’ve never seen before in the middle of an open area with little to no cover or concealment nearby and no tools to breach under fire is kind of a suicide mission that is likely to fail.

The simplest type of reinforcement is simply adding more wire.  In this instance I’ll add a single row of concertina  to the base of the existing fence on the threat side. Not a very complex obstacle by any means but it does complicate being able to get through the lower portion of the fence and frustrates trying to create a breach.  If you take this measure then it’s a good idea to make sure your concertina wire is firmly fixed to the lower portion of the existing fence (both the wire and posts) so it can’t simply be lifted up and out of the way. Burying a part of the bottom of the roll is an even better idea and if you can anchor it to the ground that’s even more effective.  Using something as simple as cut and bent rebar or cut up step in or pigtail posts every few feet will keep that concertina wire fixed. A key point here is that concertina wire is most effective when it’s slack – not pulled tight or stretched.  Once it’s in place you can add a couple of barbwire stringers (or razor tape if you have it) to the roll to keep it from expanding or collapsing. Note the illustration below:

So we’ve got a slightly better obstacle than just a standalone fence.  If you wanted to make it even more effective you could add another layer to either side of the fence.  And if you have the resources you can even create what the military refers to as “triple strand” concertina.  Triple strand concertina is three rolls of concertina wire stacked in a pyramid shape.  It’s a little more labor intensive and given the fact we already have one fence up with its wire intact unless you’re going to pull that wire you’ll have to drive more posts.  The goal is to have the two bottom rows tied to the post and the top row actually straddling the posts with the whole assembly being tied together at every possible location.  As I stated another option is to drive additional posts in front of your first roll of wire (tying it as you go).  Make sure you stagger the posts so they aren’t lined up with your existing ones.  That will give the entire assembly more rigid strength.  After you have those posts in roll out another roll of concertina and tie it to the posts.  Then you’re going to take a third roll, unroll it away from the fence, and place it on top of the other two ensuring you place it over the new posts you’ve driven.  It’s a good idea to tie as much of this together as you go and then go back later and anchor everything as much as possible.  Afterwards you can run stringers of barbwire or razor tape (similar to the single strand) to keep the assembly rigid and from collapsing.  Tying the wire together and anchoring it to the ground and the posts is imperative to prevent the threat from simply lifting the wire out of the way or cutting and rolling an entire section back.

We now have an obstacle that’s going to take some time and effort to get through.  And if you place it correctly (away from cover and concealment and within fields of observation and fire) that time translates into time that you can engage a threat.  Another point I want to touch on here.   If you go back to the entry in which I wrote about clearing fields of fire and observation remember I stated you want to clear as far into any woodline as you can well that concept also applies to obstacle fences.  Because of one time proven tactic – a threat attempting to breach an obstacle will almost always have support covering it firing from cover to its rear or flanks.  If you are trying to engage a threat attempting to breach wire and you’re taking fire yourself you’re interdiction is going to be much harder and probably less effective.  Denying that threat breaching element support by fire increases the effectiveness of your capabilities.  When we get into placement I’ll illustrate a couple of ways that you can frustrate the threat’s support by fire capabilities.

At any rate we’re up to a regular old barbwire fence with some triple strand on the threat side.  Good, but it could be better.  How can we make it better?  Add more layers.  You could create another set of triple strand on the backside as well or you could add another type of obstacle on the front or backside.  One of the ones I’ve run into that is a total pain in the ass to deal with is called “tanglefoot”.  Tanglefoot is a matrix of wire run close to the ground in an interlocking pattern designed to frustrate a threat from either running through an area or crawling along the ground. It doesn’t have to be super complex and doesn’t have to be perfectly uniform.  IMHO the most effective tanglefoot runs at varying heights and uses both tight and slack wire. You don’t want it to be so high the threat can crawl under it nor do you want it to be so low that the threat can step on it.  It also needs to be close enough that the threat can’t easily step between it.  Here’s an example used in Vietnam:

Notice how the wire is setup in a complex matrix?  In reality this wire is probably too close to the bunker (inside hand grenade range) however it will prevent anyone rushing the bunker which was probably its original intent.  No doubt there were other obstacles setup in depth to give the occupants of that bunker some additional stand off.

Tanglefoot is actually simple to emplace and very effective but it is resource intensive.  When placed stand alone you want it at a depth that a physically fit man can’t easily jump across from a run.  When combined with other obstacles you can decrease its depth however you still have to take into account changes in the ground (like dips, depressions, humps, etc.).  When placed inside woodlines it can frustrate the threats’ ability to quickly assault from cover.  In open areas if it’s put in tall grass or immediately behind a hill and it could be almost hidden until the threat is right up on it.  Not a pleasant surprise when you’re trying to move from cover to cover in an assault.  And even if the threat knows it’s there it can still help to divert the threat into an area where you can engage it (remember I referred to this as “channeling” a threat).  The illustration below shows a basic tanglefoot setup.  In this example I’m going to use 26 inch long posts made of either wood or cut down t-posts.  The t-posts will get notched to hold the wire (that keeps it from being lifted or pushed down once you tied it onto the post) and the wooden posts should have the wire stapled securely to them.  The basic pattern starts by measuring a line 12 inches from the fenceline parallel to the fence.  Then measure additional lines 12 inches beyond that.  Now segment our first line by driving posts in at least 12 inches deep in irregular heights leaving 8 to 14 inches exposed at 24 inch intervals along that line.  Once you’ve completed the first line start working on the next line  while staggering those posts so they half the distance of the first ones.  Continue on until you have a pattern similar to step 1 in the illustration below.  Once all of your posts are driven you then run barbwire stringers along the lines you originally measure out connecting it to the posts once you’ve stretched it tight (step 2).  Next you being creating your diagonal pattern by running the wire hand tight along the diagonal patterns until you’ve reached the end of your obstacle.  Make sure anytime you can tie the diagonal lines to an existing fence you do so not just wrapping it around but looping it around them.  It’s actually pretty simple in its construction but it is time and resource consuming.

One additional step you can take once you have all of your posts in before you being running wire is to cut the end of the posts to a pretty sharp angle.  I saw this done in Korea and I couldn’t help but think if you ran into that stuff at night and tripped into it that would create one helluva puncture wound.

Tanglefoot placed in front of your triple strand is going to frustrate the threat’s ability to get in close to deal with the triple strand.  Placed on the backside of the fence and it creates an area that frustrates the threat’s movement once he gets through that fence and triple strand.  So let’s add some tanglefoot to our fence:

In the above illustration I’m going to emplace at least six feet of tanglefoot on the backside of the obstacle first.  Why six feet and not ten/twenty, etc?  Six feet is a good length to prevent a threat from jumping over the wire once I add a backside fence (see below).  I’ll also add at least four feet to the front side of the concertina.  Why at least four feet? That’s a good tradeoff distance to give some standoff when the threat is trying to deal with the concertina.  Try kneeling, reaching out four feet, and doing some grunt work.  It’s hell to maintain your balance and accomplish any task that requires effort (like using wire cutters).  Once you have your tanglefoot integrated into your fence and you’re happy with it is a good time to setup any “surprises” you might want to use.  When laying in tripwires make sure you run them so they can’t accidentally be snagged and you darn sure want to run them so the threat can’t easily cut them.  Use the wire to your advantage and make sure the threat has to pull or push on it to get to those tripwires.

So we now have a fairly complex wire obstacle but I’ve got a problem.  I have livestock and I damn sure don’t want them tripping into that tanglefoot or setting off any surprises – almost a sure bet especially if you have goats or mules.  I’d also like to have one more layer of complexity to my obstacle as well.  To deal with these issues I’m going to do a little planning before I start laying in wire and add another fence on the backside.  This fence is going to be a bit different – it’ll use goat wire.  So I’m going to drive in my posts before I lay in my tanglefoot and dig a trench (I like using a tiller for this) six to eight inches deep in front of the posts.  Here’s where things get complicated and you have to be really careful or you’ll be tied up in your own obstacle.  You want to fix that goat wire on the threat side of the posts with the bottom cell below ground level BEFORE you put your tanglefoot in.  Once you have it tied to its posts then bury the bottom cell (if you have the resources to anchor the wire below ground use it).  Then working between the two fences you’ll tie your diagonal barbwire for the tanglefoot to this fence as well when you’re running it. See the illustration below:

What are the advantages of this setup?  Let’s think about it.  If I’ve placed this correctly when the threat hits it he’s going to have to deal with stepping into the tanglefoot to get to the triple strand.  Then he has to get through the triplestrand and the fence it’s attached to before he runs into another set of tanglefoot.  Once he works his way through that (and if he doesn’t set off any surprises up to that point) he still has to either cut or climb that goatwire to get through.  It’s not fool proof but it accomplishes a few critical obstacle goals.  It may reroute the threat if he’s unwilling to deal with it.  It may also expose him to my fire while he wrestles with it if I sited it correctly. You don’t necessarily have to use tanglefoot between fences.  Another set of triple strand, a razor wire obstacle, or even a natural obstacle like cacti or thorny bushes could be put in that zone.

The last couple of examples are pretty complex obstacles that would require a lot of time, effort, and resources to construct.  When planning keep in mind the most important tenet of obstacles – Anything that’s going to make it hard for the threat to get in is probably going to make it hard for you to get out.  Use your imagination, measure your resources, and think about what you’re planning from the threat’s perspective of “how much of a pain in the ass is this going to be to deal with” by mixing up the different types to create as complex an obstacle as you can given your resources and time.  As always this isn’t all inclusive, there are other types of wire obstacles and in the next entry we’ll look at a couple of other types of obstacles that serve specific purposes.  For the time being here’s a few other sources of info for your reading enjoyment.

Here’s a site with a wealth of information for those that have little to no experience with the pleasure (that’s sarcasm) of putting up fences.

The US Army’s Field Fortifications Subcourse  has a good chapter dealing specifically with wire obstacles.

Here’s a great little Book titled Wiring Obstacles by the US Army dated 1917.  Still a lot of good basic info in it.


About Treaded

Semi-retired career and contract troop. I own and maintain my own small ranch out here in beautiful rural America.
This entry was posted in Defensive Measures, Hardening the Homestead, Security Planning, Terrain and AO Development. Bookmark the permalink.

5 Responses to Defense: Obstacles Part IX: Reinforcing Existing Fences

  1. gary says:

    Check with roadway maintenance departments; use old damaged street sign post. Drive them in and cut tops at a 45 and sharpen

  2. Randy Weaver says:

    Hello, first, thank you for all you do here. I wanted to get your input on something I had read recently, no idea where or how old the posting was but basically the author said that “hog wire” fence laid just a few inches above the ground would prevent livestock from walking on it. The idea was to prevent cows and such from getting near fruit trees. The wire was easy enough for people to walk on or be removed at harvast time but the livestock were afraid to walk on it. I was just curious if that was true and if so how could something like that be tied in to an early warning system?


    • Treaded says:

      I’ve never used it in that manner but cows and horses are skittish to walk on anything that will look like it can trip them or they’ll fall into (similar to a cattleguard) so that sounds reasonable. Goats and mules will walk right through it. if there’s solid ground underneath (HH6s Nanny actually stands on top of our cattleguard balancing on the pipes).
      As far as an E/W system I’m going to cover a few different techniques in probably three or four entries down the road – just have to finish out on the wire piece first. Different types of alarms, wiring techniques, etc are coming up shortly.

  3. Pingback: Two From LF | Western Rifle Shooters Association

  4. Pingback: Defense: Obstacles Part X: Closing Some Gaps | The Lizard Farmer

Leave a Reply

Fill in your details below or click an icon to log in: Logo

You are commenting using your account. Log Out / Change )

Twitter picture

You are commenting using your Twitter account. Log Out / Change )

Facebook photo

You are commenting using your Facebook account. Log Out / Change )

Google+ photo

You are commenting using your Google+ account. Log Out / Change )

Connecting to %s