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The Most Effective Technology in Modern War Is Concrete, Argues Military Scholar

Siege warfare has become a new norm.
Image: US Army

World War I was a war of the future, where the new technologies of machine guns, heavy artillery, and poison gas turned battlefields into hellscapes of the sort that had never before been seen in war. Its defining symbol, however, became something entirely non-technological: trenches. To survive, soldiers dug holes in the ground.

21st century warfare, with its drones and precision airstrikes and satellite imagery, finds a curious low-technology analog. The battles of the Iraq War have taken place in sprawling cities and among divided neighborhoods against insurgent fighters wielding IEDs. It's a new sort of war environment, one in which block by block and house by house fighting becomes normal. Notions of front lines and flanks become quaint.


The low-tech answer to this is concrete. Lots and lots of concrete. It is, in the words of West Point scholar Maj. John Spencer, the most effective weapon on the modern battlefield. Where WWI soldiers dug holes, modern soldiers build walls.

Spencer published an essay to this effect last week and it's gotten some attention in the days since. It's worth the views—the idea that the modern battlefield might be defined by something as crude as concrete is counterintuitive and fascinating.

"Many soldiers deployed to Iraq became experts in concrete during their combat tours," Spencer writes. "Concrete is as symbolic to their deployments as the weapons they carried. No other weapon or technology has done more to contribute to achieving strategic goals of providing security, protecting populations, establishing stability, and eliminating terrorist threats."

Image: Spc. Kiyoshi Freeman/US Army

It started along the highways surrounding Baghdad. Military commanders needed some way to protect these routes from roadside bombs. Over the course of months, soldiers first lined every major highway with 12-foot high concrete walls, and then moved on to other, smaller roads. At the same time, concrete walls were going up around US military installations and encampments; within weeks, soldiers could construct a large walled compound replete with hardened guard towers.

When the 2007 surge demanded that troops clear neighborhoods of insurgents, urban environments were reshaped on-demand with walls. Concrete was used to control access to neighborhoods: A wall and a checkpoint staffed by Iraqi security forces or local members of the armed neighborhood watch Sons of Iraq (SOI) could provide some assurance that a region was free of insurgent forces, thus reducing the need for troops to hold and occupy territory in the conventional warfare sense.


Spencer was himself deployed to Iraq as an infantry soldier in 2008, where he quickly became a "pseudo-expert" in concrete. It came in slabs of various sizes where each one named for a state, he recalls: Jersey barriers were three feet; the Colorados were six feet; Alaskas were 12 feet. Guard towers could be up to 28 feet tall. They weighed anywhere from two to eight or more tons and were placed by crane.

"We wanted to achieve stability," Spencer told me in an interview from West Point. "[That] was the number one goal. And sectarian violence is the biggest kind of opposition to that." And if you can constrain the insurgents' ability to move among different neighborhoods, limit their freedom of movement, you can limit sectarian violence. "These safe neighborhoods were almost as effective as weapons."

"If you don't have a way to constrain the environment, then you have to start clearing it at your own pace," Spencer said. "You clear and then you have to put forces in and then hold that area while you move on to clear the next area."

Image: Sgt. Zachary Mott, US Army

Concrete in Iraq was produced mostly by local contractors and put into place by American troops. It was suddenly a huge industry. New factories were built, old factories were expanded. Each slab cost around $600 and Spencer estimates that the US spent several billion dollars in all on walls that in many cases would, eventually, be ground into gravel when no longer needed. They aren't meant to be permanent.

"In 2008, I was involved in the battle in Sadr City, which is a very dense urban city that is also already surrounded in a kind of cube," Spencer told me. "Many units had started to put walls up around it, but our wall was kind of the final wall."

"Every night a local crane operator would show up and would link up with our army units," he recalled. "You have, you know, the armored Humvees and Bradley fighting vehicles in a convoy and in between there you have a crane. And then you have large semis and flatbed trucks with all the concrete. The local civilian crane operator would get out and start setting up and then we would provide security while he's maneuvering the crane and concrete into position. And then you have a ladder and a soldier has to go up to the top of that and unhook it as it's placed in that position."

It's a different image of battle, certainly, but one that's likely to be seen again in the future as warfare continues to occur in complex urban environments. Spencer argues that military planners need to be considering concrete as a component of larger strategies, as a default tool in the modern arsenal. Cities subdivided into mazes of grey concrete is a dystopian thought, for sure, but if combat is to occur in them at all, it's be difficult to argue that block by block military occupation is any less so.