The young men of the 1879 Yale University varsity football team look like an eager and capable bunch, but they don’t look much like football players, at least not how we know them today. Dressed in button-up tunics and knickers, with leather shoes on their feet and little beanie caps on their heads, they might, were they to take one step onto a modern field, look across the line at their opponents—heavily muscled, helmeted, and armored—and promptly retire to the bar for brandy and cigars, their honor bruised but their bodies still intact. In their day, though, they were a fearsome bunch, among the best and most physically brutish players in the country, and were surely big men on campus—none more so than their captain, a lithe, mustachioed twenty-year-old named Walter Camp, who would enjoy minor glory as a player, but would go on—as an adviser, inventor, coach, sportswriter, rule-maker, and general celebrant and impresario of all things sport—to become regarded as the father of American football.

If Camp, who died in 1925, appeared this fall for a game at the Yale Bowl (to say nothing of watching Alabama or Notre Dame, or an N.F.L. game) he’d likely marvel at the speed, size, and skill of the players; the fervid, costumed crowds; the massive apparatus of television production; the array and cost of products for sale—in short, at all the many parts of the great American football apparatus. But as Julie Des Jardins, a professor of history at Baruch College, demonstrates in her incisive and comprehensive new biography of Camp, the modern game still bears his imprint, both on and off the field. Camp invented the concept of downs, the line of scrimmage, the snap, the basic formations of the offense and defense, and is said to have thrown the first forward pass on record (though he would later campaign, unsuccessfully, against adding it to the sport’s official rules). For years, he selected and touted the top college players in the country in his All-American lists. He gave the field its gridiron design and coined the names for the positions of quarterback, halfback, fullback, guard, and tackle. What’s more, Camp’s ideas about football—what it represented as a uniquely American sport, what it demanded of men and gave them license to do—which he identified from the very beginning, and proselytized to anyone who would listen, are still as relevant and contentious as they were then.

Camp didn’t invent American football. Its origins are murky, dating back to the mid-nineteenth century, and it owed much early on to English rugby. By the time that Camp, as a seventeen-year-old high-school senior, stood on the sidelines in New Haven, in 1875, one of a thousand or so spectators for a contest between Harvard and Yale, the basics of the new American game had taken shape: it involved two sides who kicked or carried a large ball toward opposite ends of the field; points were awarded for touchdowns and kicks, tackling above the waist was permitted. Mostly, it was churning, violent chaos, and Camp loved it.

The only child of a school administrator and a housewife, Camp moved to New Haven with his family when he was five years old. When he became a student at Yale, he devoted himself to sports, especially football. He carried a ball with him to class and made the varsity squad as a freshman. Though five feet ten and just a hundred and sixty pounds, he was a fierce competitor; in a game that first fall against Columbia, he knocked a player with such force that his opponent’s head cracked against the hard ground. “I was sure that the man’s head had broken open like an egg-shell,” he would later remember. (Helmets were still a few decades off, and institutional concerns about concussions even further away.) After the play, Des Jardins writes, Camp was filled with such remorse that he asked to be removed from the game. Yet while Camp may have been ambivalent about the pain he inflicted on others, he had few qualms about violence in the sport more generally. There were worse things for a young man, he later wrote, than “a sprained ankle, a twisted knee, or even a broken nose.”

The physical danger endemic to football was not a lamentable byproduct of the game for Camp and other of its early proponents, but instead the source of its real value. “Camp portrayed football, more than any other burgeoning sports, as providing the forced discipline, sense of danger, and physical hardening white college men needed to retain power in the modern age,” Des Jardins writes. Football was the right sport for the right kind of young man—namely, élite, upper-class, white men who had grown up coddled and soft, and who, with the closing of various American frontiers of masculine action, appeared destined to live that way as adults, too. Its hardness was the whole point. “Better make a boy an outdoor savage than an indoor weakling,” Camp wrote.

After graduating, Camp enrolled in the medical school at Yale—less, Des Jardins argues, for a love of medicine than for an excuse to stick around campus and play on the team and continue in his role as an unofficial “ambassador” of football. He later dropped out of medical school and took a sales job at the New Haven Clock Company, where he’d work for the next forty years. But football was his true passion, and a partial source of income, for the rest of his life. The game did not yet have professional coaches, but Camp essentially played that role for his former Yale team, in addition to organizing and officiating games, leading newly formed rules committees, and spreading the word about football in newspaper and magazine articles and in books, including “American Football,” the sport’s foundational text, published in 1891.

As the game grew in popularity, it became clear that the best way to play, or at least the best way to win, was to be more physically ruthless than the other team. Camp led the charge to take football further from its rugby foundations by reducing the number of points that a team could earn by kicking. “Americanizing the game meant prioritizing physical force, manipulating weighty bodies over the goal line, rather than the demure flicking of the foot,” Des Jardins writes. (Camp would later explain soccer’s lack of popularity in America by noting its comparative lack of danger.) Touchdowns became the objective, and kickers were set apart as mere specialists, as they remain today.

At first, Yale cornered the market on toughness, but soon other teams began to catch on. In the early eighteen-nineties, the Harvard team found success by employing what was called a “flying wedge,” a Red Rover-style play in which the offensive side would form up in front of the ball carrier and rush wildly, with a running start, from behind the line of scrimmage, at the stationary and vulnerable defensive side. Defenses trained to meet the challenge with equal ferocity. As more college teams started playing football, more and more players got hurt, sometimes catastrophically. Several university presidents ordered the game banned. Newspapers reported shocking figures on annual football fatalities: twenty-three in 1890, twenty-two in 1891, twenty-six in 1892. Columnists condemned the sport as ghastly, an opinion that was confirmed, in 1894, during the high-profile Harvard-Yale game, which Des Jardins describes as a bloodbath: “Linemen shoved and punched, and injured players staggered about like the walking dead, clearly concussed, officials unheeding their condition.” A Harvard player broke his collarbone, another had his eyes gouged; a Yale player, knocked unconsciousness, was removed from the field on a stretcher. A well-known boxer at the time, when asked his opinion of football, was quoted as saying, “There’s murder in that game!”

This debacle marked the first of several public-relations crises for the growing sport. Camp got to work defending the game, collecting testimonials from former players, who said that football made real men of them and that they suffered no physical damage from their playing days. Dissenting opinions and contradictory facts were omitted from the final report, published in book form as “Football Facts and Figures.”

A decade later, football was more popular than ever, spreading from colleges to high schools. But as more men were playing, more were dying. Finally, in 1904, it became clear that new rules were needed to protect players from themselves. The outcry became so pitched that President Theodore Roosevelt, a Harvard man and longtime football fan, called a summit at the White House, which Camp attended, to push for changes. Two years later, new rules were codified: players could no longer rush from behind the line of scrimmage, first downs were stretched from five to ten yards to give the game more space, and, most significantly, the forward pass was legalized, making the game less about brute strength than about speed and finesse. Though he was lukewarm on the changes, Camp received much of the credit for them in the press. Roosevelt’s intervention was the moment that football became a truly national sport. There was no more talk of banning the game outright. Camp had helped to convince the country that football was something worth dying for.