Good old triple strand concertina wire.

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.

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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.

Wire obstacle.

Been there, done that, and it is a flaming pain to get every single bit out of the running gear.

Cratering Charge

Since we’re on a bit of a kick talking about the Engineers lately, here’s one of my favorite pieces of their kit.

As noted, the three primary missions of the Engineers are mobility, countermobility, and survivability. Countermobility is denying the enemy freedom of movement, usually by obstacles to block, delay, channelize or turn him. Common obstacles include concertina wire, anti-tank ditches, minefields, and abatis.

In places where a critical road route cannot be bypassed, such as a cut through a pass, cratering the road is an excellent method of delaying the enemy.

The use of explosives to move earth is something of an art and a science. Simply placing a large pile of C-4 on the road will do little. A slower “burning” explosive such as ammonium nitrate/fuel oil (ANFO) or H-6 is preferred, as it give more of a “push” than faster explosives, which are more of a “cutting” effect.

Also, a cratering charge, not surprisingly, has to be buried in the ground to have any militarily significant effect. In areas of soft soil, this can be achieved with a pick and shovel. But since we’re talking about cratering a roadway, that option is somewhat less attractive. It is both difficult and very time consuming.

The Army, therefore, came up with a novel system to quickly emplace and explode a cratering charge that requires no preparation of the site, only the charge itself, using off the shelf components to field a rather ingenious device.

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The M180 Cratering Demolition Kit is two explosive warheads and a rocket motor mounted on a tripod.

Here’s how it works. Once the tripod and charges and associated det cord and detonators are emplaced, a blasting machine is used to trigger the charge from a safe distance. The blasting machine both ignites the rocket motor and a time delay blasting cap for the main 40lb warhead. The rocket motor propels the warhead down the tripod leg. The nose cap of the warhead strikes the M57 firing device.* The M57 sends an electrical impulse to the M6 blasting cap, which sets off the det cord and the M2A4 Shaped Charge warhead. The 15 pound shaped charge warhead blasts through the roadbed and well below. The rocket, continuing along its path, buries the main warhead well below the surface. The delayed action detonators blow the main charge, and the cratering effect takes place.

Typically, three to five M180s are connected and fired together to make one really big crater.

I’ve had the pleasure of actually watching one in action. It’s quite the thump. But surprisingly, I was unable to locate a youtube of one in action. On the other hand, I did come across this clip of young Engineer officers  performing cratering while at the Engineer Basic Officer Leaders Course. First with a hand emplaced shaped charge, they break sod, then hand emplace a cratering charge.

[youtube https://www.youtube.com/watch?v=TS2GG5HFWrk]

 

 

*Yes, the same M57 used in the M18 Claymore mine

The Al-Can Highway

Since we’re on an Engineer kick, we might as well talk about one of the more impressive feats of engineering during World War II.

With the Japanese attack on Pearl Harbor, the defense of US possessions in the Pacific took priority. Among the many outposts of America that were to be defended, and late serve as a springboard for attacks on Japan, were installations in Alaska, then a territory of the US. There was no overland route to resupply our forces there. The only method of supply was via ship. This method was thought vulnerable to Japanese surface raiders and submarines, and further imposed requirements on the already strained shipping available. Accordingly, the US entered into an agreement to build a road from British Columbia, through the Yukon to Alaska.

Construction began in March of 1942 on a route that would stretch almost 1400 miles. Incredibly, by October of that same year.

Now, this wasn’t exactly a modern superhighway. It was in the vernacular of the day, a “pioneer road.”  Most of the road was a simple dirt scraping through the forested wilderness.  Many stream crossings were simple fords, or at best, expedient log bridges. Travel along the route would be possible for 2-1/2 ton 6×6 trucks, but your family car would be helplessly bogged down. Nevertheless, a road route was now available to support the buildup of forces in Alaska, as well as to support the transfer of airplanes to the Soviet Union for Lend-Lease.

As soon as the route itself was finished, improvements along the most troublesome parts of the route began, principally replacing  fords with bridges and grading some of the worst steep spots.  Gravel roadbed was laid along many stretches, particularly those areas that had been subject to permafrost, and other troublesome sections of road were replaced with “corduroy” road.  Corduroy road is a roadbed of logs laid spanwise across the roadbed to support vehicles to prevent them from sinking into a quagmire of mud. It if from this bumpy surface texture that the pants take their name.

Under the agreement signed with Canada, immediately following the war, the road was transferred to Canada, and has been improved and paved almost continuously since then. It is still the only road route from America’s lower 48 to Alaska.

Demographics meant that the Army in World War II would draft large number of African Americans. Policy dictated that they would serve in roughly proportion to their population in the US, about 10 percent. Ergo, roughly 10 percent of the Army in WWII would be comprised of African Americans. But the policy of barring blacks from serving in combat units (with the exception of a relative handful of all black units) meant that supply and support services such as the Engineers would have disproportionately large numbers of black units. Again, the near ban on black combat units meant that divisional engineer combat battalions would be white, so those general service engineer regiments and separate battalions were often all black units. The majority of engineer general service regiments (EGSR) tasked with the construction of the Al-Can Highway were Negro units. Comprised mostly of unskilled laborers (due to poor literacy in the pre-war black population), they still managed to operate every bit as well as the all white EGSRs they served alongside.

Engineering

We have spent considerable time over the years discussing the infantry-artillery team in combat, and likewise, the infantry-armor team (and when we discuss them, by implication, we’re also discussing artillery supporting them in the same matter as the traditional infantry-artillery team).

One supporting arm we haven’t discussed as much as we should is the Engineers. For most of the Army’s history, the Engineers were at the top of the food chain. They were the intellectuals of the Army. From the founding of West Point, to the cusp of World War II, virtually all of the top graduates of the Military Academy served in the Engineers. Indeed, from its founding until 1866, the Corps of Engineers ran the academy. Unlike the other arms and services, who were focused solely on their wartime missions, the Engineers also had another role outside of wartime, providing the expertise to build the nation’s infrastructure for defense and commercial operations. Virtually every canal, navigable waterway, and port in the United States has been a Corps of Engineers project. Many of the Works Progress Administration programs of the Depression Era were supervised by Army Engineers, often of astonishingly junior rank. Even to this day, the CoE has a nationwide mission in developing flood control projects and similar activities upon the nations waterways.

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When I think of the Engineers, I tend to think of the Combat Engineer battalion assigned to divisions to act as part of the combined arms team. Traditionally, the three missions of the combat engineer units were mobility, countermobility, and survivability.

Mobility, from where I was at the bottom of the food chain, was generally understood to be the reduction of natural and manmade obstacles to combat units on the battlefield, such as bridging rivers, breaching minefields and wire obstacles, and making emergency repairs to roads on the forward edge of the battle area.

Countermobility was just the opposite, not surprisingly. Emplacing minefields, wire obstacles, anti-tank ditches, cratering roads, and demolishing bridges to deny them to the enemy.

Survivability meant to assist in the construction of fighting positions for armored vehicles, dismounted troops, and artillery, and digging in  command posts, and supply dumps. Given the relatively small number of engineers assigned to a division (and the similarly small number assigned to today’s Brigade Combat Teams), that’s a pretty full plate.

Further, Engineers are the only organization that have a stated mission to be prepared to fight as infantry. Now, every soldier, and every unit in the field, is expected to be able to fight to some extent. But those units are expected only to be able to provide a limited self defense capability. They are not expected to mount attacks and defense a given sector against the main body of the enemies forces. And it is a foolish commander that uses his valuable engineering assets in this manner in anything other than an emergency. But the fact remains that combat engineer battalions are organized and equipped to fulfill that mission should a critical need arise. In effect, they are a built in reserve for the unit commander.

But the Engineer mission is far more than merely breaching obstacles at the front. They have a mission that extends from the very tip of the spear to the most rearmost echelons any theater the Army might find itself in. Indeed, until the Engineers get crackin’, there IS no theater of operations.

When the US began building up forces in Saudi Arabia at the beginning of Desert Storm in August of 1990, the region was very austere. While there were some port facilities and airfields already extant, the infrastructure was nowhere near capable of supporting the massive force eventually deployed. The combat elements of a modern army are quite capable of moving off road, but the logistical elements need a somewhat more robust road port, road and depot network to sustain large forces with the massive amounts of fuel, ammunition, rations, spare parts and other sundries a modern army requires. Simply providing potable water to 400,000 troops in the desert is a massive challenge.  The Army’s Engineers built or contracted for the needed infrastructure in record time. Similarly, as the US built up its forces in Afghanistan, and later Iraq, the Engineers were there to provide the network of roads and bases that comprised the supply chain sustaining US forces in theater. We Americans have long taken pride in our troops abilities as fighting men (and women). But we should not forget that it is our institutional ability to build and sustain forces in the field that truly sets our services apart from the rest of the world, and the Army Engineer’s role in that ability.

We’ll shortly take a look a historical look at Engineers in World War II, especially one of the more remarkable types of organizations, the Engineer Special Brigades, and the key role the ESBs played in both Normandy and in the campaigns in the Pacific Theater.

UPDATE:  D’oh!!!  Craig reminded me that not only has he written about the CoE’s extensive efforts in flood control, his post had ‘splodey as well. Go watch some explosions!

More Here.