While football flounders in an ethical mire, a sibling game—one with origins in the same medieval brawls over a pig’s bladder—is poised to enter the big leagues of American sport. Outside North America, rugby is already the world’s second-most popular game, behind soccer, and a major money-maker. The 2011 Rugby World Cup attracted a cumulative audience of nearly 4 billion viewers. The 2015 World Cup, which culminates on Saturday in a face-off between Australia and New Zealand, has topped that figure, with television coverage in 207 territories, including Libya and the Scott Station near the South Pole.

And yet rugby’s true final frontier and television’s biggest prize isn’t the South Pole, but the United States. As Tony Collins explains in his new book The Oval World: A Global History of Rugby, rugby is becoming American. The U.S. men’s team, defeated in this year’s pool matches, is seeded 16th in the world; the women’s team is fourth. A Chicago-based consortium is planning a national, all-pro league, modeled on the league that launched American soccer in the 1970s. If the prospect of Americans embracing rugby like they do other major sports seems outlandish, it seems even more remarkable when you consider the game’s exclusionary origins, as detailed Collins’s groundbreaking book.

To be sure, rugby enjoyed a surge of popularity in the U.S. a century and a half ago, but it didn’t last. Ivy League colleges in the Northeast, joined by colleges in California, took up a sport that had already sprawled outward from its Victorian roots at the British boarding school it’s named after. Emigrants had carried rugby across the British Empire, and expats in the U.S., as in Europe, had started clubs. But even gold medals for the American rugby teams in 1920 and 1925 weren’t enough to prevent it being eclipsed altogether in the following years by football, which Collins notes was quickly growing from a regional to a national game.

Even compared to football, rugby has a particularly violent reputation—unlike the American sport, rugby is fast, fluid, and played without helmets or body armor. Growing up in London, I played rugby from the age of 8 to 18, every winter, four afternoons a week. Even in the snow, we scrimmaged wildly in cotton shirts and shorts, socks rolled down to the ankles. The terms of the game themselves conjure up a vision of animalistic mayhem: “rucks,” when players converge after a play goes awry and the ball is on the ground; and “mauls,” organized brawls among the eight forwards who do the dirty work on the team. (Seven backs, who do the running and kicking, support them.) Meanwhile, the classic rugby tackle is perhaps best compared to trying to grab the rear legs of a galloping pony that’s wearing cleats.​

In addition to being a rugby fanatic, Collins is also a social historian who trains his eye on the less savory parts of the sport’s history. As as he describes in The Oval World, no other game carries such a burden of snobbery and racism. Soccer, the saying goes, is “a gentleman’s sport, played by hooligans.” Rugby is “a hooligan’s sport, played by gentlemen.” The Victorians who wrote the rules believed in the amateur ideal—playing for the love of the game, not for money, which turns out to be an expensive habit. This approach thrived in the posh precincts of Britain’s public schools, where elitist bigotry did too. Rugby’s ruling class, the founders of the Rugby Football Union in 1871, despised the plebeians who also loved the game. When the clubs of England’s industrial north seceded in 1895 and formed a professional Rugby League with rules of its own, the amateur RFU closed ranks: A Union player caught talking to League officials could be banned for life.

In The Oval World, Collins does a thorough job of describing how the soul of the game was bound up in class war and imperial ambition. Faithful to the amateur ideal, the Victorian officer class believed the empire might run on money, but that the imperial character must not and needed to be strengthened in other ways. “The leaders of British society, industry, and empire had to be educated in the competitive spirit that drove the engine of economic expansion,” Collins writes. Yet rugby’s creators didn’t foresee how the rapid popularity of team sports in general would eventually create a ticket-buying public, and sportsmen who played for money.

Still, for a century, the widely beloved game remained a prisoner of its hierarchical origins. In the 1970s and 1980s, all-white Union rugby teams broke the anti-apartheid boycott and toured South Africa, where in 1974 their brawlers left their opponents looking “as if they had been in a road accident,” according to Collins. In the 1980s in England, class divisions still ran deep. The forwards had day jobs as grocers and policemen; the backs were officer class, Oxford and Cambridge men who worked as lawyers and bankers. Only in 1995, two years before Britain left Hong Kong, did the old guard surrender and professionalize the game for the first time. This came after Australians and New Zealanders threatened to secede, in pursuit of television fees that could only be garnered legally by a professionalized sport. Since then, World Rugby, known as the International Rugby Board, has modified the rules and turned the television-friendly game into a phenomenally lucrative business.

Today, the amateur ethos survives only in the most professionalized of societies: the United States, where since the 1970s rugby has caught on again quietly but dramatically. And as the rugby revival in the U.S. demonstrates, inclusion rather than exclusion is the spirit of the American game. The country has led the way in the diversification and democratization of rugby. Women’s rugby, pioneered in America in the 1970s, is now a global game too. In 1981, the first wheelchair rugby team formed at the University of North Dakota. In a second innovation, their sport, known as “Murderball,” fielded the first mixed-sex teams. In 2001, the Washington D.C. Renegades hosted the first gay-friendly rugby tournament.

American rugby has outclassed the game’s past, which is no guarantee that it will avoid the risks of popularity and a well-paid future. Yet so far, rugby has become commercialized without the corruption that disgraces football and soccer. A case can even be made that professionalization has raised the sport’s tone. With no urine testing, Collins notes in his book, amphetamine abuse had once been commonplace among the amateur teams. The Oval World describes how in 1986, the French team took a “little blue pill” the team doctor had put by their lunch plates before playing an especially intense game against New Zealand. The All Blacks’ Wayne “Buck” Shelford lost his four front teeth in one ruck, was knocked out in another, and required stitches on his scrotum after being caught on the ground in a third.

Televised rugby just might win an American fan base, but Collins doesn’t expect it to eclipse football—at least not in the men’s game. ​If the sport turns out to have staying power this time, its core ethos of fairness and balance may face a new kind of challenge with the rise of the women’s rugby team. (Even the more developed sport of soccer has seen top-ranked women’s players treated like amateurs compared to mediocre men’s players.) Now ranked third, the U.S.A. Eagles women’s team is within sight of winning the World Cup one day. If they do, or if the U.S. men’s team ever defeats England at its home base in Twickenham Stadium, the sport’s traditionalists may mourn the crushing of amateur ethics by television money, and the sullying of rugby’s soul.

Yet the moral value of rugby comes not from amateur ideals, but from the physical courage required to play the game, professionally or not. It’s a sport where mutual responsibility is assumed, where every player is the last line of defense. Pared down to its most basic elements, rugby is a kind of moral tutor, teaching “passion, pride, and meaning,” Collins says. As the sport deepens its roots in the U.S., his book offers a well-timed and deeply informed global history of the game. From now on, he seems to say, we’re all living in the oval world.