It was a beautiful day for barbarity. The brilliant mid-winter sun transformed the Gulf of Mexico’s placid blue canvas into a sparkling sea of diamonds. The ivory sands of the Mississippi coastline glistened like a blanket of fresh powdered snow as lazily drifting clouds offered periodic relief on an unseasonably warm day.

The soft, repetitive murmur of the wavelets kissing the white dunes was muffled, however, by the yells of a bloodthirsty mob gathered just yards away. Nearly 2,000 boxing fans had invaded the grounds of the Barnes Hotel on the morning of February 7, 1882, jolting the resort town of Mississippi City from its wintertime slumber. The sanguinary crowd hoped that the hotel’s emerald lawn would soon turn crimson from the soaking blood of two warriors—reigning American heavyweight champion Paddy Ryan and John L. Sullivan, the undefeated 23-year-old phenom from Boston who had awed America with his power.

From boisterous barroom squabbles to surreptitious whispers in church pews, the bare-knuckle championship had become the talk of the nation. Preacher Henry Ward Beecher warned his Brooklyn congregation against betting on the fight, but to little avail. The New York Times reported that as much as $200,000 had been wagered on the bout in New York City alone. Major metropolitan newspapers provided unprecedented coverage, and as the days remaining to the fight dwindled, trainloads of fans poured into New Orleans from as far away as San Francisco.

Boxing matches in the late 1800s were primal affairs, savage human cockfights rife with bare-knuckle brawling, wrestling, biting, hair pulling and eye gouging. In an 1879 championship bout, one slugger even poured turpentine on his hands to blind his opponent. Clashes among knife- and pistol-wielding spectators often caused more violence than the gladiators inside the ring. The savagery, corruption and gambling endemic to prizefighting roamed so far beyond the bounds of Victorian-era sensibilities that the governor of Louisiana had banned the Ryan-Sullivan affair from his jurisdiction and the governor of Mississippi ordered sheriffs to use any means necessary to prevent the championship fight from soiling his state’s turf. Fearful of “magisterial interference,” fight promoters kept the bout’s location shrouded in a cloak of secrecy as thick as the darkness that enveloped the trainloads of fans that departed New Orleans at 5 a.m. on the morning of the fight for a destination unknown.

Hours later, the train finally stopped and exhaled at Mississippi City, a small seaside resort between Biloxi and Gulfport. Fans sprinted to the battleground—the front lawn of the sprawling Barnes Hotel. Well-to-do dandies in stovepipe hats and a handful of corseted women in flowing dresses gladly surrendered five dollars for the highly coveted vantage on the hotel’s verandah, while fans of lesser means perched themselves in bare magnolia trees.

As Ryan and Sullivan came to the center of the ring and doubled-up their clenched, bare fists, the crowd pressed hard against the makeshift ring. The roar of 2,000 voices echoed off the towering Mississippi pines. Sullivan pounced like a caged tiger. It took just 30 seconds for the “Boston Strong Boy” to rock Ryan’s jaw with a wince-inducing right that buckled the champion to the turf.

For nine rounds, the challenger continued his onslaught with terrific rushes until he knocked out the feeble Ryan with a wicked right hook. Still full of energy after the championship fight, Sullivan hurdled the ropes, skipped out of the ring and streaked into superstardom.

The intense media attention and fan interest surrounding the 1882 championship bout provided a mere glimpse at the future. During his decade-long reign as heavyweight champion, the hard-hitting Sullivan was an unstoppable engine of destruction. Outside the ropes, his oversized personality, drunken binges and rocky personal life coincided with the advent of American mass media and launched America’s celebrity obsession with athletes.

The legendary spirit of the fighting Irish made flesh in Sullivan, born to immigrants who fled Ireland’s potato famine, transformed him into an idol for hundreds of thousands of Irish Americans who felt emasculated in the wake of the Great Hunger and slighted in their new homeland. By eventually insisting on fighting with gloves under the newly developed Marquis of Queensberry Rules, Sullivan also revolutionized boxing from a barbaric, outlawed bare-knuckle sport into the modern gloved spectacle we know today.

Far from being a bygone, sepia-toned relic, Sullivan’s story is a familiar one. Everything we know of modern sports—the hype machine, the press coverage, the hero worship by fans, the pitfalls of celebrity, the endorsements, the greed and ungodly sums of money, the gambling, the intersection of show business and athletics and the gossip—all appear in Sullivan’s tale. Decades before Ruth ever donned a baseball uniform, Sullivan headlined theatrical productions, sought political office, owned sports bars and hawked products for advertisers, all commonplace activities for athletes today.

The boxing fans who flooded Mississippi City on that beautiful winter day in 1882 witnessed the birth of the modern sports age, and the “Boston Strong Boy” became its first star. If sports are America’s secular faith, Sullivan is not only among the country’s pantheon of athletic gods, he is its Zeus.

This article has been adapted from Christopher Klein’s “Strong Boy: The Life and Times of John L. Sullivan, America’s First Sports Superstar” (Lyons Press, 2013).