From "Orphans Preferred - The Twisted Truth and Lasting Legend of the Pony Express" by Christopher Corbett:

In writing about Joseph (Jack) Slade in Roughing It, Twain recalled a famous and notorious published description of the bad man: "From Fort Kearny, west, he was feared a great deal more than the Almighty."

Joseph Slade was not a figment of Mark Twain's imagination. Nor was he a tall tale. Slade is perhaps the most solid example that everyone in the employ of Russell, Majors & Waddell was not enjoying a glass of sarsaparilla and the Psalms in the evening. The Central Overland California & Pike's Peak Express Company hired men who could get the job done, and some of those men were plainly outlaws. Joseph Slade was the most stunning example.

Young Sam Clemens first heard of Slade while crossing Nebraska, and he recalled a decade later in Roughing It that the bad man's name was on the lips of everyone he met. "There was such magic in that name, SLADE! Day or night, now, I stood always ready to drop any subject in hand, to listen to something new about Slade and his ghastly exploits," Twain recalled, adding, "From the hour we had left Overland City we had heard drivers and conductors talk about only three things-'Californy,' the Nevada silver mines, and this desperado Slade. "

Twain remembered that "Slade was a man whose heart and hands and soul were steeped in the blood of offenders against his dignity; a man who awfully avenged all injuries, affronts, insults or slights, of whatever kind-on the spot, if he could, years afterward if lack of earlier opportunity compelled it."

Twain prepares the reader for the eventual encounter with Slade "the most bloody, the most dangerous, and the most valuable citizen that inhabited the savage fastness of the mountains" - with a preposterous buildup.

According to Twain's version, Slade was a native of Illinois who had left "the states" and headed west after killing a man in a quarrel. Twain said that Slade had joined a wagon train headed for California at St. Joe. The first story that made up his legend took place on the trip when Slade killed another traveler. Twain and other writers about Slade report that he eventually wound up in Julesburg, Colorado-a celebrated junction on the way west where travelers either forked south toward Denver or continued on to California or Oregon. Julesburg was lawless at that time, and the stories of Slade claim that he was hired to restore order to the overland stage division centered hereabouts - a place plagued by horse thieves and outlaws. (Indians were not a serious problem here.)

Slade was eventually credited with establishing law in this territory, or at least his version of it. But this happened only after a celebrated encounter with the founding father of Julesburg, one Jules Rene (his name is often spelled Reni, Bene, or Beni), a French Canadian who had turned this station into a kind of "robber's roost." After a long period of warring, Slade killed Jules after cruelly torturing him. Twain repeated a graphic account of the long-running feud between Slade and Jules, attributing it to stories he heard on the overland and read in California newspapers.

Eventually Twain and his brother, Orion, arrived at a stage station and sat down to breakfast "with a half-savage, half-civilized company of armed and bearded mountaineers, ranchmen, and station employees. The most gentlemanly-appearing, quiet, and affable officer we had yet found along the road in the Overland Company's service was the person who sat at the head of the table, at my elbow. Never youth stared and shivered as I did when I heard them call him SLADE!"

The killer, Twain reports, turns out to be a friendly and gentlespoken soul who does not seem at all dangerous. "It was hardly possible to realize that this pleasant person was the pitiless scourge of the outlaws, the raw-head-and-bloody-bones the nursing mothers of the mountains terrified their children with. And to this day I can remember nothing remarkable about Slade. . ."

Twain ends his story of meeting the fabled badman by having Slade offer him the last cup of coffee in the pot. "I politely declined. I was afraid he had not killed anybody that morning, and might be needing diversion. "

Twain ends his account of meeting Slade by wondering if and when he will hear of him again and then reports in the next chapter how Slade was later lynched (although he begged for his life) by vigilantes in Virginia City, Idaho Territory (later Montana), who had suffered enough of his drunken and violent behavior.