During the formative weeks of trench warfare in 1914, military physicians saw their first cases of “shell shock,” a cluster of symptoms that include many signs of traumatic brain injury (TBI) and chronic traumatic encephalopathy (CTE). Soldiers became confused, sometimes abandoning their posts, with many being condemned to stand before firing squads for desertion. Others became listless, earning reputations as “shirkers” and discipline problems. Many minor cases were discharged; some were subjected to torturous experimental treatments such as electrotherapy. A few could no longer speak, while others presented with uncontrolled shaking and convulsive movements — symptoms very like Parkinson’s disease or amyotrophic lateral sclerosis (ALS, also known as Lou Gehrig’s disease), two disorders that exhibit loosened tau protein spilling into the white matter of the brain. Perhaps not coincidentally, studies have found increased prevalence of ALS in all who serve, whether during war or peacetime, regardless of military branch, while Parkinson’s has been diagnosed in World War II veterans at twice the rate of the general population. It is still unclear whether the three disorders are somehow linked.

The diagnostic techniques of 1914–1918 were unable to detect what was happening to the brains of soldiers, yet battlefield physicians did suspect at first that shell shock was the result of physical trauma, not a psychological scar. Many noted that the majority of symptoms were similar to those associated with brain lesions. Tucked between papers on venereal disease and heart problems in soldiers, the February, 1916 issue of the British medical journal The Lancet includes a Dr. Frederick Mott positing that “physical or chemical change and a break in the links of the chain of neurons which subserve a particular function” was taking place in the brains of men exposed to high explosive blast.

Unfortunately, because doctors could not see the injuries to their patients’ brains, they soon turned to other explanations. At the time, the fashionable science of invisible disorders was psychology, which ascribed these behaviors and symptoms to stress. Even Dr. Mott was convinced that the exhausting conditions of the trenches and “experiences … depressing to the vital resistance of the nervous system” played a role in the phenomenon.

Two competing explanations for shell shock emerged by the end of the war. Sympathetic professionals argued that men had suffered injuries to the mind, and that the horrors of war were too much for any man. Less-sympathetic professionals argued that these men were just not manly enough: contemporary diagnoses call them “nervous,” or suffering from “neurasthenia,” and often “hysteria” — a 19th Century term that was loaded with misogynistic meaning, inferring that shell shock victims were too feminine for the manly rigors of war.

Major W.J. Adie of the Royal Army Medical Corps, who belonged to the former group, “developed a reputation for the way he treated shell-shocked men who had lost the ability to speak.” As recounted in Canada’s History Magazine,

He lashed them to an operating table and put a constrictive gas mask on them, leaving them for a while to suffer in near-suffocation. He returned some time later and, in a soothing voice, promised to remove the mask when they said, “take it away.” For more stubborn cases, he injected ether through the mask, while, in his words, he “pricked the skin over the larynx rather vigorously with a pin.”

In the second category was Sir Andrew Macphail, the official historian of the Canadian Army Medical Corps, who declared that the condition was the result of “childishness and femininity” in soldiers.

Nevertheless, it was clear that high explosive bombardment was responsible for these symptoms, though the exact mechanism remained unclear. Soldiers seemed to be disoriented or crazed by the screaming of the shells as much as the explosions, inspiring a young signal officer named John Ronald Reuel Tolkien to write years later of warriors in Middle Earth losing their wits to the screams of the Nazgûl.

Half a century later, psychologists diagnosed “Post Traumatic Stress Disorder” in soldiers who returned from Vietnam with a range of problems, chiefly antisocial behavioral issues, from drug use and alcoholism to altered personalities and arrest records. Whatever scarring experiences these veterans had endured, many of them had also survived shelling, rocket fire, and other forms of high explosive blast under sustained high-stress conditions. It took America’s wars in Afghanistan and Iraq during the 21st Century, where the principal weapon faced by American troops has been the high explosive roadside bomb, to finally reverse this mistaken consensus that the hidden wounds of modern combat were all psychological or the result of personality deficits.

American football has followed a parallel track, and by design, not coincidence.

Contrary to Lord Wellington’s apocryphal statement that Waterloo had been won on the playing-fields of Eton, rugby took its recognizable modern form only after the Napoleonic Wars. In concept, the game somewhat resembled the musketry-era conception of battle as a grand shoving match between two opposing lines of men. The wars of the European renaissance began with men wearing armor and carrying pikes in square formations, gradually transitioning from pikes to firearms over the next six centuries, changing the shape of war.

Designed to recall Britain’s greatest war victory, rugby was soon transmitted to the United States, where Gettysburg became the lens of experience. In 1869 — just four years after the surrender at Appomattox, smack in the middle of a revolution in the scale and intensity of armed conflicts everywhere — Rutgers and Princeton played the rugby match that sports historians mark as the very first game of American football.

The men who organized this event were consciously imitating the battles that the young nation had just experienced. Born out of a rivalry over the possession of a Revolutionary War cannon, that first intercollegiate match was quickly imitated. Columbia held its own football game with Rutgers the next year; Harvard and Yale then joined in the new game; these four schools created the Intercollegiate Football Association, which later rebranded itself as the Ivy League. Their new version of rugby spread throughout the American college system during the 1880s, with the first professional league appearing in 1892.

Though the rules were quite different at the beginning — indeed, they were negotiated anew before every game — football matches have almost always begun with a kickoff, during which the opposing teams smash together, risking the first casualties of the game in a crescendo of maximal violence. With this “movement to contact” or “encounter battle” phase completed, the match transforms into an echo of von Schlieffen’s memorandum: two teams fight along a line, coming to grips with each other from position to position, day and night, advancing, digging in, using every ounce of strength to shake the opponent’s confidence in his backfield. Progress is measured in yards.

American football was thus framed from the very beginning as an explicitly masculine test of battle readiness that consciously reflected real-world battle tactics which were still developing at the same time. The pushing and shoving and hard collisions, as well as the accompanying injuries, were regarded as preparation for actual war and actual wounds. Harvard publicist Lorin Deland, the inventor of the “flying wedge” kick return, was explicitly trying to imitate the unit tactics of the era. Football teams were called “platoons” in press accounts from the very beginning; uniforms also appeared immediately. By the 1880s, every snap of the ball was preceded by a whistle, the same instrument with which countless officers led their men “over the top” to annihilation after 1914.

The relationship of football to war was always explicit from the very beginning. “What if, at the time, your side may be the weaker?” asked Yale coach Walter Camp, who called football “the Game of War,” in his 1895 Book of College Sports:

Don’t be a coward on that account. Face it like a man, and say with your whole heart that you are on the side of the men who want no chance of retreat or escape, only a fair contest and certain victory or defeat at the end of it. To what do all the technicalities amount when compared with the sincerity of men who come together to effect that result?

“Don’t take the coward’s part and try to legislate means of avoiding the issue,” he urged, using the word “coward” twice in one paragraph. Talk was cheap in the new game of football, which lent itself to authoritarian leadership. In our time, Noam Chomsky has denounced the sport as “a way of building up irrational attitudes of submission to authority and group cohesion behind the leadership elements,” a form of “training in irrational jingoism.” Coach Camp might have shrugged and said, Of course. So what?

When the United States joined the allies on the Western Front in 1917, consultant Camp brought the “Daily Dozen” mass calisthenics of his profession to the military training field. Although the specific exercises have changed, every basic trainee today still recalls the collegiate athletics training regimen of the first decade of the 20th Century whenever they grind through a PT session.

Camp was “the father of football,” both coach and referee, the acknowledged expert on the game and also its most important rule maker. He made tackling below the waist legal, then taught young men to put their heads down, charge forward with deathless courage, collide with the enemy, butting heads like wild rams. To this end, Camp ignored rules against purposefully striking another player with one’s own shoulders and head, instead coaching his teams to hit in that exact way by means of a new invention: the tackling dummy.

This violence was not incidental to the contest. The game is literally and linguistically “centered” on hitting. Blocking and tackling from a two-point stance is safer, but hitting from a three-point stance, with the greatest possible leverage, is more fun to watch. The biggest hits have always drawn the most applause, so players hit each other like this over and over. At first, they started at each other from the snap with no separation at all between their bodies, like a rugby scrum. Even Camp could see this was problematic, so he spent years championing the establishment of a neutral zone (“no man’s land”) between the teams before everyone agreed to the wisdom of his idea.

“You play the way you practice,” declared Glenn Scobey “Pop” Warner, who also taught his players to tackle opponents low and at speed in 1888. His Native American students at the Carlisle Indian Industrial School would be the beta testers for a whole new theory of the game, pioneering the forward pass and trick plays, “the team that invented football.” Yet Warner’s blocking and tackling drills were not very different from Camp’s, and they are what have truly defined the game from the 1880s until the present day. Millions of Americans have thrown themselves at each other head-first since then, over and over and over again. We will never know the full extent of the damage they did to their brains in the process.

Concussions were understood by medical science before the invention of football and they were common enough in the football games of the 1880s and 1890s. The dangers of the sport were so obvious by 1904 that there were calls to ban it, and schools did begin to drop the game, for football headlines at the beginning of the new century were dominated by obituary reporting. The Chicago Tribune called it a “death harvest”: at least 18 players died across the United States, with another 159 seriously injured, mostly at the high school level, in the same year that Japan seemingly defeated Russia with headlong, bloody banzai charges into barbed wire and machine guns.

Football had become so dangerous that the president of the United States intervened to save the game from itself. Theodore Roosevelt admired the martial qualities instilled by football and the toughness that it inculcated in young men. In “American Boy,” an essay he wrote in 1900, Roosevelt preferred “rough sports which call for pluck, endurance, and physical address.” More than just a pastime, “this athletic involvement is really a means to an end,” he said. Such games were “preparation for work that counts when the time arises, especially in defense of the country.” Both war and working class values were on his mind, and maximized violence was a good rehearsal for either future. “In short, in life, as in a football game, the principle to follow is: Hit the line hard: don’t foul and don’t shirk, but hit the line hard,” he concluded. “I believe in rough games and in rough, manly sports,” he told an audience at the University of Minnesota in 1903. “I do not feel any particular sympathy for the person who gets battered about a good deal so long as it is not fatal.”

But now in 1904, he was decrying the “brutality” of the game.

To resolve the public relations crisis, Roosevelt insisted on several changes. The length of the match would be set in stone; football games would be limited by precision timekeeping, with the clock stopped for injured players rather than adding “injury time” as in rugby or soccer. The industrial working day was divided into four quarters by two brief breaks and a lunch break; football would be divided into four quarters by two field changes and a halftime period, with a horn announcing the end of each half — just like a factory floor shift.

Responsive to his demands for reform, collegiate rulemakers legalized the forward pass in every game, fixed the values of touchdowns and field goals at six and three points respectively, set the exact measurements for every field, and changed the distance needed for a first down from five to ten yards in order to discourage teams from simply ramming the ball down each other’s throats on every snap.

These changes came in time for the 1906 season. Injuries declined a bit, spiking again in 1909, whereupon the Intercollegiate Athletic Association of the United States (which later became the National Collegiate Athletic Association, or NCAA) further eased the forward passing rules and encouraged lateral running plays to fend off another wave of criticism. The game was still dangerous, but politics demanded that they be seen making the effort, anyway. A “committee on casualties” tracked the results until 1915, reporting a drop in fatalities at all levels of the sport before declaring its purpose fulfilled and disbanding in dubious triumph.

During that same groundbreaking year, five western collegiate football clubs vied with teams east of the Mississippi, making the game truly national for the first time. The Tournament of Roses, which had been disappointed by its first experiment with college football in 1902, tried the game again by hosting a match between Washington State University and Brown. The Bruins team featured halfback Fritz Pollard, the first black All-American. Known for hitting hard and moving the pile forward, Pollard went on to become history’s first black professional football player, and then the first black professional head coach. Now known as the Rose Bowl, the game has been played on January 1st or 2nd every year since 1916.

That Pollard rose this way during the same moment in which a racist President Woodrow Wilson promoted the film Birth of a Nation, inspiring a nationwide revival of the Ku Klux Klan, points to football’s leveling effect on American attitudes toward race, a phenomenon intrinsically linked to the violent risks associated with the sport. His career also mirrors the rich diversity of the Western Front, where millions of troops and laborers from all around the world formed a polyglot army along the allied side. Regarded with suspicion by their white generals, in 1917 American Negro soldiers would find their paths of glory had been opened up by Senegalese Tirailleurs from West Africa during the first days of the conflict.

And like Fritz Pollard, every one of the American negro soldiers who arrived in France during 1917 and 1918 wore a helmet as they marched to the trenches. Through a conspiracy of historical circumstance, steel brain protection had become as ubiquitous on the Western Front as leather headgear on the gridiron.

Next time: 1915, the Year of the Helmet.