question: How effective is barbed wire / razor wire as a defensive measure in combat? I feel like in movies all they do just make two snips and continue on.
comment: It's good at slowing people down since actually making that clearing takes time, and during that time you are shooting at them with pre-ranged weapons since you know where the slow-down will happen. It also forces them to go through only a few locations, since not every soldier is going to make a separate opening.
passages: A commonly seen alternative is the placement of a few strands of barbed wire at the top of a chain link fence. The limited mobility of someone climbing a fence makes passing conventional barbed wire more difficult. On some chain link fences these strands are attached to a bracket tilted 45 degrees towards the intruder, further increasing the difficulty.
   A more modern version, allowing quicker dispersal and providing the advantage of being hidden more easily, are caltrops, though items bearing close similarity (small balls with spikes) had been in use for most of antiquity. Many variants were also used, such as boards with metal hooks, as described during battles of Julius Caesar.
  
  Passive fortification—ditches and obstacles such as dragon's teeth and Czech hedgehogs—were used as anti-tank measures during World War II.
  
  Section::::Historical methods.:Anti-infantry.
   One example of perimeter protection still in use is razor wire fencing. While U.S. ranchers in the 19th century kept the cattle in and the rustlers out with barbed wire, World War I saw the advent of specialized barbed wire to secure military operations. The 1965 escalation of the Vietnam conflict was accelerated by the successful penetration of ten foot high concertina wire (razor wire) fencing around Camp Holloway. Variations of this type of perimeter protection were used prolifically throughout the 20th century. Booby traps, electric fencing, watch towers and night flares were also vigorously employed to keep enemy forces out.
   A point man usually preceded each team – crawling silently through defenses, probing with his fingers to detect and neutralize obstacles, while the others followed behind. Sometimes gaps in the wire were created by tying down strands to make an assault corridor. Woven mats might be thrown over barbed wire to facilitate passage. Sappers often used Bangalore torpedoes made from blocks of TNT tied to bamboo poles to blast open assault routes. Attack routes often took unexpected avenues of approach, such as through the trash pits of US Firebase Cunningham in 1969.
   It is possible that a point of entry can be created by a precision explosive device to catch the adversary by surprise.
  
  Section::::Principles of assault.:Speed.
   Simple rows or clusters of sharpened sticks (nowadays also known as punji sticks), and the use of small caltrops have been a feature of anti-infantry warfare since antiquity. However, due to the difficulty of mass-producing them in the pre-modern age, they were rarely used except in the defense of limited areas or chokepoints, especially during sieges, where they were used to help seal breaches. Increasing ease of production still did not prevent these methods from slowly falling out of favor from the late Middle Ages onward.
   The Q-Net was first sent to combat in Afghanistan in 2010. When soldiers saw the armor system, they were skeptical and concerned about its effectiveness. On September 19, a vehicle patrol equipped with Q-Nets was ambushed. At less than 100 meters distance, insurgents fired a volley of RPG rounds, followed by machine gun fire and then another RPG. The soldiers moved forward of the ambush and repelled the attack. Following the firefight, they found that the vehicles had taken three direct hits from RPGs and had not penetrated. They detonated at the nets, stopping them from penetrating the armor. One soldier commented, “All of the soldiers whose vehicles were hit by RPGs are alive today and still in the fight.”
   Caltrops are still sometimes used in modern conflicts, such as during the Korean War, where Chinese troops, often wearing only light shoes, were particularly vulnerable. In modern times, special caltrops are also sometimes used against wheeled vehicles with pneumatic tires. Some South American urban guerrillas such as the Tupamaros and Montoneros, who called them "miguelitos," have used caltrops to avoid pursuit after ambushes.
  
  Section::::Modern methods.
  
  Section::::Modern methods.:Explosives.
   Though described in the Office of Strategic Services catalogue as a cross between a machete and a bolo, it was actually based on the Royal Welch Fusiliers Trench Knife of World War I, and was designed as a pure combat knife. It has a broad, leaf-shaped blade sharpened the full length on one side, and from the tip to half of the other side. The entire blade is coated with a dull matte finish to prevent detection at night from stray reflections.
  
  Section::::Use.
   Section::::Area denial.:Anti-personnel.
  
  Section::::Area denial.:Anti-personnel.:Caltrops.
  
  Simple rows or clusters of sharpened sticks (also known as punji sticks), and the use of small caltrops have been a feature of anti-infantry warfare for a long time. However, due to the difficulty of mass-producing them in the pre-modern age, they were rarely used except in the defense of limited areas or chokepoints, especially during sieges, where they were used to help seal breaches. Increasing ease of production still did not prevent these methods from slowly falling out of favor from the late Middle Ages onward.
   Caltrops are known to have been in use since Roman times and may have been used earlier: the concept was familiar to the 4th century BC Greeks, who used rocks, brush, nets and trees placed in the path of enemy conveyances on land or ensnarement devices hidden under water to achieve the same result: stop the enemy or suspected hostile in his tracks for examination or to prevent or limit incursions. Contemporary caltrops look something like large jacks from the childhood game. Placed in the path of oncoming wheeled or tracked vehicles, they are meant to foul wheels, destroy tires and tracks, and incapacitate vehicles.
   Methods for soldiers to face this threat were a small wheeled steel plate that was slowly pushed forward in front of the soldier to shield them from bullet fire as they crawled, shielded machine gun carts, the MacAdam Shield Shovel or systems like the mobile personnel shield among others. When the obstacle was reached, access holes in the shield allowed the attacking soldier to cut away at the wire obstacle with pliers from behind the protection of the armored shield.
  
  Stormtrooper platoons included ballistic shields in their equipment list, as infiltration was one of their specialities.
   Working with barbed wire was a nasty job under any circumstances, but when you were handling it in the dark and within a hundred yards of rifles and machine guns that would shoot at the least sound, you were doing one of the most nerve-wracking bits of work that could possibly be imagined...the slightest move might mean death for half your party.
   The Snider was notably powerful. Rudyard Kipling gave a graphic depiction of its effect in his poem, "The Grave of the Hundred Head":
  
  poem
  
  A Snider squibbed in the jungle—
  
  Somebody laughed and fled,
  
  And the men of the First Shikaris
  
  Picked up their Subaltern dead,
  
  With a big blue mark in his forehead
  
  And the back blown out of his head.
  
  /poem
  
  Section::::Variants.
   StunStrike
  
  The StunStrike is a wireless electroshock weapon being developed by XADS. It is in various sizes from rifle size upwards, with various ranges. It is intended to incapacitate men and pre-detonate IEDs and incoming RPGs. 
   Starting in the late 1960s, barbed tape was typically found in prisons and secure mental hospitals, where the increased breaching time for a poorly equipped potential escapee was a definite advantage. Until the development of reinforced barbed tape in the early 1980s (and especially after the September 11, 2001 attacks), it was rarely used for military purposes or genuine high security facilities because, with the correct tools, it was easier to breach than barbed wire. Since then some military forces have replaced barbed wire with barbed tape for many applications, mainly because it is slightly lighter for the same effective coverage and it takes up very little space compared to barbed wire or reinforced barbed tape when stored on drums.
   Section::::Modern use.:Law enforcement.
  
  The tomahawk has gained some respect from members of various law enforcement tactical (i.e. "SWAT") teams. Some companies have seized upon this new popularity and are producing "tactical tomahawks". These SWAT-oriented tools are designed to be both useful and relatively light. Some examples of "tactical tomahawks" include models wherein the shaft is designed as a prybar. There are models with line/rope cutting notches, cuts in the head allowing its use as a wrench, and models with broad, heavy heads to assist in breaching doors.
  
  Section::::Modern use.:Modern tomahawk fighting.
   Whenever there was time and opportunity to plan and emplace wire obstacles during the First World War, it was standard practice to deploy designs that would channel and concentrate attacking troops, through avenues of approach, herding them like cattle into designated killing zones i.e. fixing multiple screw pickets of wire running diagonally, away from the protected zone. This meant that a belt-fed machine-gun such as the Maschinengewehr 08 sited along that diagonal line had easy targets to enfilade when attacking troops were blocked from advancing by the wire and then massed together in a line.
   BULLET::::- The History of Barbed Wire About.com
  
  BULLET::::- The Wildlife Friendly Fencing project
  
  BULLET::::- Papers, 1878-1938, of Texas rancher and co-inventor Isaac L. Ellwood in Southwest Collection/Special Collections Library at Texas Tech University
  
  Patents – (about 570 were issued):
  
  BULLET::::- accessed September 21, 2006
  
  BULLET::::- – Lucien Smith, Kent, Ohio, "Wire fence" – "rotary spools with projecting spurs" (June 1867)
  
  BULLET::::- – William Hunt, Scott, New York, "Improvement in Fences" – "sharpened spur wheels" (July 1867)
  
  BULLET::::- – Michael Kelly, New York City (!), "Improvement in Fences" – "thorny fence" (1868)
   One example is "low wire entanglement", which consists of irregularly placed stakes that have been driven into the ground with only some 15 cm (six inches) showing. The barbed wire is then wrapped and tightened on to these. An enemy combatant running through the barrier, which is difficult to see, is apt to trip and get caught.
  
  Section::::History.
   Section::::Uses.
  
  Various modern military groups also use attack dogs, primarily for sentry purposes. The dogs are trained to defend their post and attack any possible intruders. It is also reported that dogs have been used in psychological torture against prisoners of war.
   In the 1980s, a number of programs, such as the IAI Harpy or the AGM-136 Tacit Rainbow, integrated anti-radiation sensors into a drone or missile air frames coupled with command and control and loitering capabilities. This allowed the attacking force to place relatively cheap munitions in place over suspected SAM sites, and to attack promptly the moment the SAM battery is visible. This integrated the use of a drone as a baiting decoy with the attack role into one small and relatively cheap platform in comparison to the alternative wild weasel jet fighter.
  
  Section::::History.:Evolution into additional roles.
   The traditional barbed wire used since the late 19th century and into the present day was made from two mild steel wires twisted together, usually of about 12 or 14 gauge, with about 15-30 twists per metre. Steel barbs were attached every 10–20 cm. Barbs had either two or four points, with the two point design using somewhat heavier and longer barbs. The relative merits of two point vs. four point barbed wire are the subject of deeply held views among many farmers and ranchers, to the extent that both types are still made today.
   The multiple blades of a razor wire fence are designed to inflict serious cuts on anyone attempting to climb through and therefore have a strong psychological deterrent effect. Razor wire is used in many high-security applications because, although it can be circumvented relatively quickly by humans with tools, penetrating a razor wire barrier without tools is very slow and difficult, giving security forces more time to respond.
  
  Section::::Use.
   Back at base the patrol members congratulate each other on the morning's work and there is a debriefing with accounts of at least one Taliban fighter supposedly found alive but severely wounded in the ditch. There are further insinuations that any movement within the ditch would have represented a possible threat and that it was thus deemed necessary to spray the enemy fighters with another volley of bullets just to be sure.
  