Leonardo DiCaprio went through hell to play indestructible fur trapper Hugh Glass in The Revenant. But how tall is the tale that inspired it? Michael Punke, US ambassador to the World Trade Organisation, wrote the book on which the film is based, and the man DiCaprio was imitating is based on a true story.Hugh Glass was a fur trapper, one of the hard-driving mountain men of the early 19th-century American West, an obscure cousin to more mainstream American folk heroes like Davy Crockett.Most of what we know of Glass's life is conjecture: he was literate and left little trace in the historical record. He is mentioned in the papers of some of his superiors, marking him as challenging, hard to handle. And there's evidence he was attacked by a bear. In fact, the bear attack is why Glass is remembered at all. The story became frontier legend within months of its happening, set down in 1824 by a Philadelphia lawyer with literary aspirations, and carried to all corners of the US in newspapers and journals.The attack - of which no direct eyewitness account exists - happened in the summer of 1823, five months after Glass had joined a fur-trapping expedition in South Dakota. On the banks of the Missouri River, he stumbled across a grizzly and her two cubs. Startled, she set upon him, ripping his scalp, puncturing his throat and breaking his leg. Hearing his cries, his companions rushed to help.Glass was close to death. The leaders decided two men should stay with him until he died and bury him. These were John Fitzgerald and Jim Bridger, played by Tom Hardy and Will Poulter.For two days they watched over him, but Fitzgerald convinced Bridger to abandon Glass, laid him in a grave and departed.Gravely injured, Glass summoned the energy to drag himself to a spring, the first step in a six-week-long crawl back to the nearest encampment.Some said Glass killed and ate a rattlesnake; he awoke from sleep to find a grizzly licking maggots from his wounds.The length of his crawl swelled from 128km to 160km to 321km. His story became more elaborate: he had been kidnapped by the French-American pirate Jean Lafitte as a young man, and captured by the Pawnee tribe.It's a disappointment when one reaches the story's end. Glass finds Fitzgerald and Bridger, but, instead of taking revenge, he forgives them both. ..