FLORENCE, Italy -- A young man lies spread-eagle in the center of a sand-covered arena, blood streaming from a gash above his eye. The guy who opened up this wound is straddled across his chest, pinning him down. All around them, more men are brawling in a terrifying tangle of fists and knees, shoulder charges and thrown elbows.

Lending a surreal edge to this scene is the combatants' attire. While some are bare-chested and others wear T-shirts, every one of them is clad in a pair of puffy-legged, brightly striped, 16th-century replica pantaloons.

They are playing calcio storico fiorentino -- Florentine historical football -- or, as many locals here know it, calcio in costume -- football in costumes. A distant forerunner to modern sports such as soccer and American football, it most closely resembles a blend between mixed martial arts and rugby.

Calcio storico doesn't have many rules limiting contact, although striking an opponent from behind is prohibited. Tackling from behind is allowed, however. ANSA/AP Photo

Two teams of 27 players, or calcianti, battle to maneuver a ball into the opponent's goal, at opposite ends of a playing field measuring roughly 88 yards by 44 yards. Beyond that basic objective, even some participants are fuzzy on the details, with more than one describing the game as having "about three or four rules." With the chaotic nature of the game, it's hard to tell when rules have been broken -- for spectators and officials alike. When spotted, egregious violations result in expulsion.

The essential restrictions are as follows:

No striking an opponent from behind (striking refers to punches, kicks and similar tactics; rugby-style tackles are still permitted).

No striking an opponent who is already on the ground. You may pin somebody down, however.

No ganging up. If an opponent is already physically engaged with one of your teammates, you may not touch him unless he is carrying the ball.

Games run continuously for 50 minutes, with no breaks and no substitutions. If a player leaves the field, he may not be replaced. To lose even one player, under such conditions, especially at the height of one of Italy's hottest summers on record, can be devastating.

And so, the young man with the gash over his eye waits patiently and allows his blood to soak into the sand. A medical team will arrive in a minute or so to stem the flow as he lies right there beneath his opponent. His day is only just getting started.

Bianchi teammates train the day before their final match against the Rossi. Players don't get paid but practice for three months leading up to the once-a-year tournament. Antonio Masiello

NOBODY IS PAID to play calcio storico. It is strictly an amateur pursuit, and many of those who participate do not even consider it a sport. "Because it isn't," Fabio Selvaggio, a player for the reigning champions, the Bianchi di Santo Spirito, said in Italian. "It's a historical recreation."

However it's defined, calcio storico is certainly a demanding pastime. There are only four teams in Florence, and they compete in just one official tournament during a typical year. It is a straight knockout, with two semifinals and then a championship game, so even in a successful season, the most a team can hope to play is twice.

And yet, teams practice three times per week for three months leading up to the June tournament. Each team might carry as many as 60 or 70 players on its roster, despite the fact only 27 can play in a game. Not even the withdrawal of the traditional reward for the victors -- a prized Chianina cow -- has made a dent on participation.

So what drives the calcianti to take part? None could be ignorant of the risks involved. To a man, every player who spoke for this story said he feels afraid when he steps into the arena. At a dinner hosted by the Bianchi on the night before the final, it was not hard to pick out the scars and broken noses this game had bestowed on its veterans.

The game doesn't stop for medical crews, who enter the field of play to treat players. Each team starts a game with 27 men, a number that can dwindle due to injury because substitutions are not permitted. Justin Setterfield/Getty Images

Selvaggio was candid in admitting his initial sense of horror. "I went to my first game when I was 8 or 9," he said. "I had a soccer coach who played for the Rossi. He took me along to watch, but I didn't know what it was beforehand. It left a really ugly impression on me.

"I had no idea that I was going to see people taking punches, getting kicked to the ground. When I saw my coach struggling, I started to cry. I was yelling at my dad, 'Take me home!'"

It took years for Selvaggio to lose that sense of panic and to see the game in a different light. Like many other boys in Florence, he wound up playing a diluted version of calcio storico with friends as a teenager. Tackling was permitted but not punches -- although fights sometimes broke out.

By 20, he had learned to love this game and joined a training session with the Bianchi. Eighteen years later, although he has a family and a job as a painter/decorator, still he comes back for more. "Because of the adrenaline," he explained. "There is definitely an element of wanting to measure yourself up against other people, to show that, 'Hey, I'm stronger than you.'"

A Bianchi player, bloodied but unbowed, struggles to his feet during the championship game. Filippo Monteforte/AFP/Getty Images

While that last point is a common theme, there is not one single reason why people play. For some it is a natural extension of their passion for other contact sports, undertaken alongside boxing or rugby. For others, tradition and community play an essential part.

To fully understand this game requires an understanding of the Italian concept of campanilismo. Throughout the country, there persists a fierce streak of localism -- with many people feeling a greater sense of belonging to the streets around their local church tower (campanile) than they do to the nation or even their city as a whole.

This culture is embedded within calcio storico. Each of the four teams is named after a church that, in turn, represents a historic neighborhood of Florence. The Bianchi (Whites) are affiliated with Basilica di Santo Spirito, the Rossi (Reds) with Santa Maria Novella, the Verdi (Greens) with San Giovanni and the Azzurri (Blues) with Santa Croce.

"For a little boy born in the neighborhood, the dream is to wear that costume. Of course, out of 10 lads, only two will succeed -- because it's not a game for everyone." Emiliano Venturi, Bianchi head coach

Priests from each church bless their team's flag at special ceremonies held in the buildup to each year's tournament. Father Giuseppe Pagano, the prior at Santo Spirito, has performed marriage ceremonies for players and baptized their children.

He spoke optimistically of the Bianchi's role as a rallying point for the community. Even outside of the three months of the year when the team is training, it seeks to deploy its influence for positive ends -- mobilizing its 800 members for charitable fundraisers and blood drives.

Father Pagano acknowledged that he did not love the violence of calcio storico, but he encouraged spectators to look beyond. "I have seen some beautiful moments when they follow the rules correctly," he said. "Some wonderful scenes, like a footballer on top of his opponent, who had him pinned down for a while so he couldn't move, offering him a bottle of water. I've seen that many times."

Supporters of the Bianchi (Whites) were in a festive -- and feisty -- mood before the final. Antonio Masiello

For players who grew up locally, the opportunity to defend one's colors is a powerful motivating factor. Emiliano Venturi, first-year head coach of the Bianchi, has always lived close to Santo Spirito. His father played for the team and then coached them, and now he has followed that same path.

"For a little boy born in the neighborhood, the dream is to wear that costume," he said. "Of course, out of 10 lads, only two will succeed -- because it's not a game for everyone."

To play calcio storico, you must either be born in Florence or have lived there for a minimum of 10 consecutive years. Even within that context, however, Venturi believes that retaining a core of players from the Santo Spirito community is essential to the success of his team.

"We Bianchi are different," he said. "We have players from outside this neighborhood, of course, but anyone can spot the ones from here right away. You can see it because they play with a different spirit, a different mentality. When you get to the game, they explode."

Fans of the Santa Maria Novella Rossi (Reds) show their support at the final. Games are played in the plaza of the Basilica di Santa Croce. Antonio Masiello

SOME HISTORIANS believe that calcio storico has its roots in harpastum, a ball game used as a training exercise by legionnaires and gladiators at the height of the Roman Empire. The modern version, however, draws from a different military tradition -- that of the short-lived Republic of Florence.

Today, games are preceded by a procession through the city, featuring cavalry, crossbowmen and foot soldiers carrying a colorful cache of medieval weaponry. These rituals are an homage to the most famous calcio storico game, played in 1530.

The people of Florence had overthrown the ruling Medici family and declared themselves an independent republic, but they found themselves under siege by a combined force from the Holy Roman Empire and Spain. To show strength, a game of calcio storico was arranged in Piazza Santa Croce, with an ostentatious march through the city beforehand.

A Rossi player throws a punch at a Bianchi opponent. One-on-one, no-holds-barred fights are a strategic part of the game, not an aberration. Striking is disallowed only from behind or when an opponent is on the ground. FILIPPO MONTEFORTE/AFP/Getty Images

The 10-month siege would end in defeat, but that game remains a symbol of local pride and defiance. "I can see, from the outside," chuckled Fabrizio Valleri, another veteran for the Bianchi, "how you might think we're all mad."

Mad perhaps, though less for this celebration of the past than for the ferocious passions of the present. All four teams take part in the procession before the final, including the defeated semifinalists.

This year's championship game between the Bianchi and the Rossi threatened to spiral out of control before it had even begun, as supporters of the Bianchi lobbed bottles of water at the Azzurri players. The players responded by chucking them right back, one sailing inches over the head of a young female fan.

The Bianchi had reached this year's final in controversial circumstances, having been awarded a semifinal victory after an Azzurri player refused to leave the field when sent off by the referee -- a scene which culminated in police entering the field.

The defending champion Bianchi get fired up as they enter Piazza Santa Croce before the final. The temporary arena outside the church seats 4,800 fans. Antonio Masiello

Happily, there would be no repeat of the scene on this occasion. The Azzurri players eventually moved away from the end containing the Bianchi fans before hostilities could intensify further. The 4,800 spectators who packed into Piazza Santa Croce's temporary arena would instead be treated this time to a game that would become an all-time classic.

At the start, as always, there is chaos. A game of calcio storico begins with a tipoff. With 54 players packed into such a tight space, not to mention referees plus a nonplaying captain and separate flag bearer for each side, the sense of congestion is overwhelming.

Gradually, though, patterns of play emerge. The ban on striking a fallen opponent leads to an inevitable process of whittling down, with players effectively pairing off in hand-to-hand combat -- using whatever method of brawling works, including fisticuffs, kicking and body slams -- until one controls the other on the ground. Typically, the team which wins possession from the tipoff will shift the ball back to a deep position and protect it while this scenario plays out.

Eventually, when the number of upright players has thinned, someone will make a move. The team with the ball might launch an attack -- sometimes deploying prepared plays, with lead blockers or misdirection and an attempt to flip possession to a teammate. Or a defender might seek to force the action by rushing after the ball carrier.

The players who remain upright tend to slow down as the game progresses. Each contest lasts 50 minutes, with no breaks or substitutions. Antonio Masiello

In either scenario, taking the initiative carries risk. Navigating a field strewn with bodies is not straightforward. Those fighters who have won their individual battles wait like alligators in a muddy river, ready to launch off the man they have pinned and snap into the legs of passing prey.

Takedowns can be brutal. Even for a seasoned watcher of contact sports, to see a ball carrier leveled by a knee to the spine is jarring. At one stage in the final, a player from the Bianchi demolishes an opponent with a move straight out of pro wrestling -- a German suplex to slam his victim head-first onto sand and stone. Even the assailant looked horrified afterward at the realization of what he had done.

It was the Rossi who claimed an early lead. A quirk of calcio storico is that attempts to score can give points to the opposition. Attackers are awarded one point, or caccia (literally, a "hunt"), for throwing or putting the ball over a chest-high wall into a net that extends about three feet higher than the wall and runs the entire width of the field, but if a shot is too high and hits the fence above the net, their opponents get a half-point instead.

The victorious Bianchi team celebrates after defending its championship thanks to a late goal -- or caccia -- scored on a half-court heave. Antonio Masiello

So it was that the Rossi jumped ahead by 1½ cacce to zero. More than 20 minutes had elapsed before the Bianchi finally got on the scoreboard, with a half-court heave from second-year player Lorenzo Ardito. After that, though, they quickly moved into the ascendancy. With nine minutes to go, the Bianchi boasted a 2½-cacce advantage.

It should have been enough. Instead, fatigue and fear set in. Attempts to shield the ball and run out the clock unraveled before a sustained counteroffensive. The Rossi retook a 5½ to 5 lead with two minutes left after a sweeping team move straight through the heart of the opposition.

Never had the arena looked more like a battlefield. Teams are obliged to switch ends after each goal, but by this stage, players from both sides -- caked in sweat, blood and sand -- struggled to walk. Bodies lay battered and broken, filthy bandages offering scant protection to shattered noses and open wounds.

The Bianchi got the ball back, but there was no plan. Their captain continued to bark out instructions in the manner of a defiant field general, but his men were too shell-shocked to respond.

"I thought I'd missed to be honest, because I didn't see where the ball went. But then I heard the roar of the crowd." Lorenzo Ardito, describing his half-court, game-winning goal for the Bianchi

With 60 seconds remaining, the ball found its way back to Ardito. As he would remember it afterward, his legs could barely carry him. "Fabrizio Valleri was there shouting at me, 'Go!', and I said to him, 'I can't. I can't run any more Fabi.' He said, 'Stop breaking my d--- and go!' He said, 'I don't give a f--- if you can't run anymore, you need to do it anyway.'

"So I took the ball, and I went five meters, but there were two men in front of me, one to my left and one to my right. There was nowhere for me to go. So I said to myself, 'Just shoot.' I thought I'd missed to be honest, because I didn't see where the ball went. But then I heard the roar of the crowd."

It was his second half-court caccia of the day. Where the first had sailed straight into the goal, this one fell short before a kind bounce carried it perfectly up and over the wall. The Bianchi supporters at the western end of the stadium exploded. Ardito started to cry.

Still wearing his Bianchi pantaloons after the final, Nicola Matarrese pops the question to his girlfriend in front of the Basilica Santo Spirito. She said yes. Paolo Bandini for ESPN

ABOUT AN HOUR after the end of the game, a young man with a cut above his eye kneels down in the middle of the Piazza Santo Spirito. The whole Bianchi team walked here directly from the game, just under a mile away, not stopping even to get changed. The winners received a heroes' reception, from beer-swigging 20-somethings to the grandmas leaning out of windows and waving torn strips of dishcloth.

But there is still one more piece of business to attend to. The kneeling man is proposing to his girlfriend. In front of everyone, she says yes.

His name is Nicola Matarrese, and he started playing for the Bianchi in 2014. Earlier that morning, at the end of the team's final training session, he had explained -- speaking in English -- what he loves about calcio storico.

"I'm not someone who goes around looking to punch people in my normal life," he said. "But when I was younger, if I did get into fights -- even without wanting to -- I would feel a part of myself that I never felt.

"Time slows down. You don't feel any more pain, because the adrenaline doesn't let you. And afterwards, when it goes well, you feel really proud, charged up. You trust more in yourself. I've always been a person that has a hard time trusting himself. I am not a bold one. So I searched in calcio storico for those same feelings."

This day, at least, he appears to have found them.

(Video courtesy: Calcio Fiorentino, a feature-length documentary by We Are Buzzers.)