Hugh Glass, the protagonist of the story, never was chased off a cliff, cut a dead horse open for warmth or had a half-Pawnee son. But the frontiersman played by DiCaprio lived a life even more fantastical than any film.

This story first appeared in the March 4 issue of The Hollywood Reporter magazine. To receive the magazine, click here to subscribe.

Before a grizzly tore a hunk of meat from his rump and lobbed it to her squalling cubs, Hugh Glass was just a middle-aged pirate who had abandoned ship, then dodged two tribes of cannibals only to witness his friend being roasted alive. And then things turned really nasty.

That's the story, anyway. But it's not the one told in The Revenant, the Alejandro G. Inarritu-directed Oscar favorite, in which Leonardo DiCaprio's Glass is chased off a cliff, recalls his Pawnee wife, eats raw buffalo liver — and mainly, drags his grizzly-ravaged body hundreds of miles through a wintry frontier, driven by bloodlust for the men who had left him to die.

The real Glass, however, made much of his journey in late summer. And he had no Pawnee wife. Even the liver is not a sure thing.

To separate mythology from biography, it helps to remember that the film is based in part on a 2002 work of fiction, which itself is based in part on the three earliest written and largely forgotten accounts of Glass' adventures. None of those authors knew Glass, and one of them, a novelist, wrote the forgettable sequel Monte Cristo's Daughter. Thucydides, these guys were not. But their accounts, as well as letters, testimony, trapper memoirs and a rich oral history, are what is left regarding Glass' life.

Based on those sources, this much is certain: Glass was alive, he survived a grizzly attack and he died. There is no evidence he had a Native American wife or girlfriend, or that he had a son by a Native American woman, or that he plunged off a cliff on a horse, or that he gutted and climbed into a dead horse to stay warm or for any other reason.

Glass lived in Pennsylvania, where he might have had a wife and two sons whom he abandoned. He was a sea captain already in his 30s when pirates attacked his ship off the coast of what is now Texas in 1819. The pirate captain offered Glass a choice: Join their crew, or join the scores of bleeding, gutted, naked, screaming and drowning men, women and children bobbing in the choppy waters below. Glass joined.

After a year of pillaging, kidnapping, killing and the like, Glass and another pirate jumped overboard and swam toward Campeche (now Galveston), the primitive headquarters of Jean Lafitte, who, it turned out, was Glass' pirate boss' boss. The two deserters slunk north toward St. Louis, the westernmost locus of American civilization. They took special care to avoid, to the east, the Karankawa, notorious for eating settlers (tribesmen called the dish "long pig"). The duo couldn't stray too far west, though, because there dwelled the slightly pickier Tonkawas, who included only severed human hands and feet in their diet (to ingest extra strength and speed).

On they pressed, away from these man-eating tribes and Lafitte's band of murderers and toward Comanche, Kiowa and Osage, the former two scary, the latter really scary (the Osage eschewed scalping in favor of decapitation). When Glass and his pal ultimately were captured, 1,000 miles after emerging from the water, it was by Pawnee, which should have provided a measure of relief. Alas, the Loup branch of the Pawnee regularly offered human sacrifices to the god of the morning star — usually young girls from the village. But an exception was made for a couple guys who represented the vanguard of an invading, land-grabbing, genocidal force.

A gang of Pawnee stripped and tied Glass' friend to a stake. As Glass watched, they stuck slivers of resinous pine into his friend's flesh, then lit them. When it was Glass' turn, he bowed before the chief, then reached into his pocket and produced a vial of cinnabar, the flaky red mineral then found in Texas and used around the world for makeup and pottery. War paint, too. The chief was impressed by the gift, as well as the sangfroid with which the white man presented it. Somehow, the pirate turned mutineer turned fugitive escaped the flaming porcupine treatment and became an honorary Pawnee.

Other than omitting a futile attempt by Glass to climb a tree and an early on-target gunshot, the grizzly attack depicted in 'The Revenant' largely is accurate.

He learned lance throwing, tomahawk chopping, and how to break and suck the marrow from buffalo bones. He ate his share of dog (don't judge). It was during this period that he likely procured his legendary and beloved rifle, the mighty and thunderous .54 caliber Hawken to which Glass grew profoundly attached and that later would cause him so much trouble.

After two years, in January 1823, Glass headed east with the chief to meet with the U.S. Superintendent of Indian Affairs in St. Louis. Afterward, the chief returned to lead his tribe while Glass stayed in town. He answered an ad placed in the Missouri Republican by the Rocky Mountain Fur Company, which was seeking 100 men to pack up and leave fancy duds, womenfolk and saloons behind to head into the Rocky Mountains. There, for $200 annually, they would trap beaver.

Men who didn't respond to the ad were enlisted from "grog shops and other sinks of degradation," according to a recruiter. Many would go on to form the sweaty, calloused core of the country's mid-19th century trapping force. It was risky, hard labor that favored the ornery. So maybe it's unsurprising that the trappers tended to be some of the more profane, violent, nature-despoiling, aboriginal land-trespassing, wildlife-poaching, gun-toting cusses ever to range the Rockies.

The party, led by Gen. William Ashley, set out on the Missouri River in early March, and except for one man falling overboard and drowning the first day, and three others being blown to bits when someone lit a pipe too close to a pile of explosives, the trip began smoothly. At least until Ashley went ashore to talk business with the Arikara (aka the Rees). Could Chief Grey Eyes and his warriors, by reputation suspicious and at times murderous regarding trespassers, spare 50 horses? Why yes, Chief Grey Eyes replied, as long as Ashley could spare a few kegs of gunpowder. A deal was struck, goods exchanged and most of the crew set up camp on a sandbar near the Arikara village. They would continue downriver in the morning.

All went without incident that evening, notwithstanding the throat-slitting of young Aaron Stephens, one of the many trappers who had visited the Ree village to celebrate the procurement of horses by fornicating with a village maiden.

The Rees attacked in the morning, wounding Glass and killing 15 of his companions. Which brings us to the film's first scene, with Leo dodging arrows and barely making it to the boat that took the trappers downriver to safety.

The film skips over the counterattack and subsequent siege of a Ree village that involved Ashley's men, another trapping party led by a Lt. Andrew Henry, 250 U.S. soldiers and hundreds of Sioux, who harbored a deep and abiding antipathy for the Ree. It was the first military encounter between the U.S. and Native Americans in the West, and relations pretty much went downhill from there.

John Fitzgerald and the teenager named Bridger did volunteer to stay with Glass until he died, and they did betray him, but the famed trapper’s quest ended without bloody vengeance in the mountains. In real life, Glass mostly just wanted his rifle back.

But back to the film — namely, that grizzly attack: Glass left Ashley's group to join Henry's (don't ask), and early in the journey, Henry sent two of his now roughly 30-strong group to hunt some meat, telling the rest, including Glass, to stay put. But our protagonist had never liked orders. Also, he hankered for some berries.

He was standing in a berry patch when Ol' Ephraim — that's what mountain men back then called grizzlies, even females — charged. Glass shot her with his rifle. It was a good shot, but Ol' Ephraim kept charging. Glass ran to a tree, but as he began to climb, O.E. grabbed him, threw him to the ground and tore some meat out of his rear. She tossed the meal to her cubs, who probably had never tasted man before (odds are they liked it). Then Ol' Ephraim returned her attention to Glass. She raked her claws across his back, bit him about the head and shook him like a rag doll. Glass moved in close and slashed the bear repeatedly with his knife. He tried to yell, but what came out was a kind of high-pitched gargling, as his throat had been torn open and was gushing blood.

The grizzly fell, dead either by Glass' shot or by those fired by two hunters who had heard the commotion. Fellow trappers bound Glass' wounds as best they could, using sweaty, soiled pieces of fabric ripped from their shirts. The next morning, having abandoned their boat, the group marched on, carrying Glass on a litter made from branches.

It slowed them down. They knew hostiles were nearby. On the fifth day or so, Henry offered cash (accounts vary between $80 and $400) to any two men who would stay with Glass until he died, then meet the others at his namesake Fort Henry.

One volunteer, an otherwise forgettable figure, was named John Fitzgerald. The other was a teenager named Bridger. They kept Glass comfortable and waited for him to die.

After five days, though, the men had a talk (which Glass reportedly later told another trapper he'd overheard). No one had expected Glass to live this long, and no one would want the pair to stay. Glass was going to die anyway, Fitzgerald told the kid. It was only a matter of time before Ree or Cheyenne found them. And besides, they had already earned their money. The two men left Glass next to a nearby stream, underneath a berry bush. Just in case.

Fitzgerald and Bridger took Glass' rifle, knife, tomahawk and flint; if they showed up empty-handed, Henry would have asked where the weapons were, and they wouldn't get paid.

In the film, Glass has a half-Pawnee son whose murder fuels his fierce pursuit of justice. There’s only one minor problem: Glass never had a half-Pawnee son.

But Fitzgerald never tried to suffocate Glass, as he does in the film, nor did he murder Glass' beloved half-Pawnee son — mostly because Glass didn't have a beloved half-Pawnee son. But seeking vengeance against a child killer is box-office gold.

The two minders set out for Fort Henry, and while the film depicts their journey as perilous and semi-epic, it was neither. They arrived two days after the others, displayed Glass' armaments and collected their reward. While the duo's conduct was dastardly by modern sensibilities, leaving their sure-to-die comrade wasn't what got mountain men talking. They were a hard lot with an affinity for risk management. Heinous and unforgiveable to mountain men, however, was taking a man's only means of survival — his tools.

As for what happens next — Glass' solitary crawl to Fort Kiowa, which comprises the bulk of The Revenant — all we have to go on is the savaged trapper's testimony, as passed on to a bunch of lying, hard-drinking louts with nicknames like Pegleg and Liver-Eating, who, in turn, relayed the account to reporters and writers of not much greater repute.

Still, one can ascertain with high probability a few things: One of Glass' legs was broken, and his throat had been mangled so terribly that he'd never speak in the same voice again. He would lie next to the stream for five days, subsisting on a large rattlesnake he killed with a sharp stone. (Filmgoers might have gone for the rattlesnake eating. Go figure.)

He did crawl, and then crawled some more, and after that, he limped. The film got that right.

He did not get chased off a cliff, nor did he crawl inside a horse carcass for warmth. He did not meet a Native American with a sly sense of humor who tossed him a buffalo liver. Perhaps he ate some liver on his sojourn, but the truth is, he ate far more dog. Dog eating was not such a big deal back then. The Comanche thought it was disgusting, true, but it was a staple of the Sioux diet. The Kickapoo revered dogs, believing they had spirits like humans and lived in heaven after death. The Kickapoo bottle-fed their dogs, kept their paws from the dusty ground, washed and swaddled and sang to them. They also ate puppy stew.

But enough with the dog-eating. What about the buffalo? Glass did, in fact, eat a calf that was being worked over by wolves. And yes, if the wolves hadn't gotten to it first, he probably ate the liver. And he did shoo the wolves away, but he waited till he saw they had eaten their fill.

Did he burn with rage and seethe with the compulsion to seek justice, to kill the men who had betrayed him, as the film depicts? You bet he did.

Three books on the life of Hugh Glass were written long before Michael Punke's 2002 novel, The Revenant, including the closest thing to a historical account, 'The Saga of Hugh Glass,' which was published in 1976.

But not for child murder — he just wanted his gun back. His beloved and trustworthy Hawken. And if he had to crawl and limp 350 miles to kill the bastard who stole it, so be it. The film doesn't get into the whole man-rifle bond too much. It also doesn't mention the few days Glass spent with some friendly Sioux, who welcomed him to their village, where they cleaned the maggots from his back wound and poured vegetable juice on it.

Glass kept walking. After many weeks, he joined six French traders at Fort Kiowa, who he thought might drop him off near Fort Tilton, where he suspected the rifle thieves would be. After six weeks he parted ways with the Frenchmen. Just a mile later, they were butchered by Ree. Some Ree spotted Glass and gave chase, but a Mandan on horseback swept in, pulled him aboard and took him to his village. Mandans generally didn't like Ree. The Mandan villagers made a big deal over him. For supper? Man's best friend.

Glass then decided to go to Fort Henry, about 400 miles back in the direction from which he'd come. He never floated downstream in frigid water (it would have killed him), but he did stop at a fort to ask after his two sworn enemies and to catch up on mountain man gossip. There was another Ree attack that he managed to survive. There was a stretch where he subsisted on more bison calf, but now, stronger, he simply walked into a vast herd, ran down a calf, killed it, cooked it and ate it.

Can you blame Inarritu for leaving out so much? Who wants to see a dog-and-calf buffet? Who would believe a guy went through all that trouble for a rifle? Too many miles, too many Ree attacks, too many arrows. The film already runs two hours and 36 minutes.

Glass eventually found Bridger at Fort Henry, and Bridger thought he was a ghost. Instead of killing him, Glass lectured the kid and told him he knew Fitzgerald had persuaded him to leave. Then Glass invoked God and told Bridger to behave better in the future.

Revenant's Glass finally tracks down Fitzgerald, wounds him, then floats him downstream to a gang of Ree, who finish the job. But that's not what really happened. When Glass arrived at Fort Atkinson in 1824, after another long trek, he learned that while Fitzgerald was indeed present, he had enlisted in the Army. A captain named Bennet Riley informed Glass that he could not kill a soldier — if he did, he'd be tried for murder. When Riley heard Glass' story, he offered to fetch Glass' beloved rifle back. What a reunion it must have been.

The film's final shot is of a terribly wronged but righteous man, peering with grit and hard-won wisdom into a forbidding but conquerable wilderness. Not even a Texas state school board would quibble with that vision of how the West was won. If you like Manifest Destiny, this ending is for you.

Another popular version of the Glass legend has him suf­fering and crawling, but instead of dispatching his arch-enemy, he finds himself swollen with empathy and love, and turns his chiseled, manly cheek and forgives Fitzgerald, as he did Bridger. This too syncs with our notions of how the West was won, or conquered, or not exactly stolen. Forgiveness works about as well as vengeance, as long as you get other stuff right.

What actually happened was more complex. Glass tried his hand at trading in New Mexico, didn't like it and went back to trapping. Then Europeans developed a taste for cloth hats, and the trapping business dried up. Wagon trains started coming, too, and along with them women, children, dogs whose owners objected to them becoming a source of protein. Civilization.

Fitzgerald was never heard from again. Bridger went on to establish, in 1842 in southwestern Wyoming, the first resupply post for settlers on the Oregon, California and Mormon trails, opening up the path west and effectively ending the era of the mountain man. And the ne plus ultra of those unruly, undisciplined, comfort-spurning creatures?

Glass endured, as the world he knew best faded away. He took a job with a new fur company. He trapped some himself. He told stories about the old days, including some juicy ones about grizzlies and rattlesnakes. Some say his greatest talent was in creating and polishing the Legend of Hugh Glass.

In the winter of 1832-33, Glass was living at Fort Cass, a new garrison built near the junction of the Yellowstone and Bighorn rivers. He worked as a hunter, procuring meat for the trappers of the American Fur Company, owned by John Jacob Astor. One cold morning in the spring of 1833, he and two other hunters left the fort looking to kill a bear or two. They hadn't walked far, and it was considered safe territory. As they made their way across the frozen Yellowstone River, 30 Ree on horseback surrounded them.

They took Glass' clothes, his gear. Then they scalped him.

Nothing heroic about his death. Nothing tied to the American dream or the nobility of pioneers. Glass had grown overconfident. He had grown careless. He had grown old.