Michael Vlahos has written a whopper of a poorly-reasoned article for The Atlantic, and there are numerous points that should be refuted.
Vlahos thinks that we should have encased the armies of World War I in body armor. This was not possible for a number of reasons. The main reason why was national pride; no nation mobilizing for war at that stage of human history was willing to admit that their troops were not "with" God. The collective naivete of the armies that were activated and sent to war in August, 1914 were all "chosen" to execute the national will. Encasing such men in body armor was not a choice for that and several other reasons. They did not know then what we know now, and no one expected their "modern" armies to use Medieval body armor. How absurd.
I think the best part of his article focuses on helmets. He is correct in his assertion that the helmets were, almost uniformly, terrible. However, during the Iraq War, the US Army discovered that the kevlar helmets in use--the supposed height of technological advancement--were inadequate when used to protect soldiers from Improvised Explosive Devices (IEDs). Special modifications had to be used to make the helmets safer, and this effort had to be funded by civilians. We were terrible then, and not so good now, in other words, but technology marches on.
World War I was fought, initially, with tactics gleaned from the Franco-Prussian war: large bodies of troops were expected to advance, wheel, and encircle other formations. These units were delivered to the front as quickly as humanly possible; troops were already forced to carry rations, ammunition, and their own shelter; wagons were brought behind the armies with other essentials. It would have been impossible for these units to travel as far as they were expected to travel with any extra weight. They were expected to march dozens of miles and then assault other formations.
This would not have been possible with heavily weighted infantrymen on soft ground; in Europe, there were rail lines but the road system was inadequate. Armies were thus organized around rail lines and the importance of using trains to move troops meant that as many men as possible had to be crammed into boxcars. What they carried, to pay tribute to Tim O'Brien, meant as much then as it does now. We have a vastly different delivery system for logistics and we have troops that are now much larger and more physically fit.
The vast majority of engagements in the early days of World War I were fought in wooded areas and where troops sunk into wet ground. Think of the muck of Ypres, for example. Think of the campaign through France and the geography that the armies faced. Many more men would have foundered in the mud or drowned near the great rivers where the battles were fought if they had been asked to maneuver in body armor.
Also, consider these issues.
One, the timetables of mobilization would not have worked with troops encumbered by body armor. They were equipped and marched and sent by train to the various fronts based on strict plans that did not accommodate "extras" or anything of that nature. The troops in the German Army were expected to defeat France in a set number of days. When the German battle plan was executed, men began falling out of the ranks with heart attacks and exhaustion. Despite the fact that the continent had spent decades "militarizing" itself, troops fell out of battle in droves because they were not prepared for the shock of continuous engagement with the enemy.
Two, it would have been impractical for men of the early 20th Century, who were shorter and thinner than we are now, to have worn battle armor and then engaged in a series of battles like the battle for France. They would not have been able to advance or move quickly enough and, because the early battles of the war were fought over open ground, the casualties would have been much higher because slower men would have been exposed to more fire. Attacks were generally "rushed" and used rudimentary tactics. Flanking movements were tried, and many of the men fought or traveled on horseback, making body armor a cruel thing for a horse to have to carry.
Three, artillery fire against massed groups of infantry was known to kill because of concussive effects. Body armor would not have saved any of the men whose internal organs were ruptured by artillery fire that never put a projectile into their bodies. Since many of the men wounded by fragments were wounded by artillery, and since many of these wounds resulted in sepsis, it is possible that body armor could have save some lives. However, it would have slowed men down and made them less responsive to incoming fire.
The gradual arming of troops in body armor throughout the rest of the 20th Century meant finding a way to adopt the technology to modern standards. tactics were radically altered by World War II but, despite all the hype about "mobilized warfare," most troops were still expected to carry their gear and march long distances, making body armor impractical. Body armor has only thrived in situations where troops can be delivered to the battle in armored personnel carriers.
In point of fact, no one has wanted to go to war in body armor. Where much smaller and less fit men from Medieval times staggered under the weight of armor and breastplates, men in Vietnam, for example, staggered in the tropical heat in their flak jackets, often tossing them away. In the Iraq War, and in Afghanistan, troops often removed plates from their heavy flak vests and ended up being wounded.
Advances in battlefield medicine have saved untold numbers of lives; the quick evacuation of troops has saved more lives, in my opinion, than better body armor. Men in World War I died of things like infection much more quickly because of the soil composition of northern France, for example. They were ravaged by disease and by lice, and infections sent them to the rear almost as fast as the wounds suffered from futile attacks.
How would body armor have saved the men against lice? Against infection? Against the rotting of their feet in wet conditions? I guess I'm not understanding how it would have made that great of an impact.