James Butler Hickok arrived in Springfield, Missouri, in the summer of 1865, fresh off a stint as Union scout and spy during the Civil War. The 28-year-old Illinois native was already known locally as “Wild Bill,” but there was little at the time to distinguish him from the countless other would-be gunslingers and cardsharps drifting through the American frontier. That would all change on July 21, when Hickok strode out to meet a former Confederate soldier named Davis Tutt in the Springfield city square. The duel that followed vaulted “Wild Bill” to national fame.

Just how Hickok and Tutt came to be glaring at one another down the barrels of their six-guns is not entirely clear. Both men were known to haunt Springfield’s poker rooms and saloons as semi-professional gamblers, and some witnesses claimed the pair had once been friends. The bad blood may have originated in a dispute over the affections of a lady, but it’s also possible that lingering Civil War tensions were to blame. Some reports even alleged that Hickok had killed one of Tutt’s friends during the war.

Whatever the source of the enmity, the Hickok-Tutt feud finally boiled over on July 20, 1865. That night, Hickok was playing poker at the Lyon House hotel when Tutt confronted him about a $35 debt from a previous card game. Hickok countered that the sum was only $25 and said he had a “memorandum” in his jacket pocket to prove it, but Tutt was unconvinced. He snatched Hickok’s beloved Waltham pocket watch off the felt and declared he would hold it as collateral until the debt was settled. When Hickok protested, he also threatened to flaunt the timepiece in the town square the next day. A seething Wild Bill warned that Tutt wouldn’t manage the stunt unless “dead men can walk.”

Hickok and Tutt spent most of the next day arguing over the watch and the poker debt, but according to witnesses, neither man seemed particularly eager to “slap leather” against the other. The former pals even tried to settle the dispute over a glass of whiskey before Tutt grew frustrated and stalked away. Sometime around 6 p.m., Tutt reappeared near the Springfield courthouse wearing Hickok’s watch. Wild Bill walked out to meet him from across the town square, his hand dangling next to one of the Colt Navy revolvers strapped to his sides. “Dave,” he warned, “Don’t you come across here with that watch.” Tutt ignored him and began sauntering in Hickok’s direction, his hand hovering over his own gun. “Dave, don’t come any closer!” Hickok shouted. As the two men inched to within 75 yards of one another, they suddenly drew their pistols and took aim.

Wild Bill Hickok as he plays in a card game. Stock Montage/Getty Images

“At that moment you could have heard a pin drop in that square,” witness Richard Bentley Owen later recalled. “Both Tutt and Bill fired, but one discharge followed the other so quick that it’s hard to say which went off first.” In the end it didn’t matter who was faster on the draw. Tutt’s shot flew harmlessly over Wild Bill’s head, while Hickok’s bullet found its mark. Some accounts say he let Tutt shoot first and then fired his own weapon after steadying it on his left hand. “Bill never shoots twice at the same man,” Owen noted, “and his ball went through Dave’s heart.” After gurgling, “Boys, I’m killed,” Tutt staggered a few steps toward the courthouse and fell dead. The bloody exchange had lasted just a few seconds.

Hickok was arrested shortly after the showdown and charged with manslaughter, but he managed to post bail with the help of Owen and a few others. At his trial in early August, Tutt’s allies testified that Wild Bill had approached their friend with his gun already out and shot him in cold blood. Hickok’s supporters countered that Tutt drew first and that both men fired simultaneously. As evidence, they presented Tutt’s pistol, which was missing a single bullet from its chamber. The gun was enough for frontier justice to carry the day. Believing the showdown to be a fair fight, the jury found Wild Bill innocent after only a few minutes of deliberation.

James Butler Hickok, known as "Wild Bill" Hickok, circa 1873. Adoc-Photos/Corbis/Getty Images

However pointless it might have been, the killing of Davis Tutt would prove to be Hickok’s ticket to Old West stardom. A few weeks after the standoff in the market square, Colonel George Ward Nichols arrived in Springfield and wrote a story about Wild Bill for Harper’s New Monthly Magazine. The article’s account of the Tutt shooting was only mildly exaggerated, but other sections painted Hickok as a walking tall tale. Nichols wrote that Wild Bill had killed 100 men; that he’d once singlehandedly fought off a gang of 10 bandits; and that he rode a seemingly magical horse that obeyed his every command. When the story went to print in February 1867, it immediately became a bestseller. Gushing accounts of Wild Bill’s exploits appeared in several major newspapers, and dime novelists capitalized on the public interest by penning such titles as “Wild Bill, the Indian Slayer” and “Wild Bill’s First Trail.”

The Harper’s story made Hickok the most famous man on the frontier, and he spent the next few years adding to his legend while working variously as a wilderness scout, lawman, “Wild West” show performer and gambler. He was involved in a few more shootouts in Kansas and Texas, but it was his duel with Davis Tutt that truly entrenched itself in the lore of the Old West. Similar “quick-draw” showdowns became a staple of dime novels, and they later found their way into legions of big screen Westerns such as “High Noon” and “The Good, the Bad and the Ugly.”

As Wild Bill’s own death would eventually prove, the realities of frontier violence were usually much less glamorous. In August 1876, Hickok joined a poker game at the No. 10 Saloon in the rugged mining town of Deadwood, South Dakota. The aging desperado had a habit of sitting against the wall to prevent anyone from getting the drop on him, but on that day the only open chair had left him with his back facing the door. While Hickok gazed down at his cards—supposedly two pairs of aces and eights—a man named Jack McCall crept up behind him and shot him in the back of the head at point blank range. Wild Bill was dead before he ever had a chance to reach for his gun.