By 1856, Kansas Territory had become the testing ground for the nation's deepest division. The Kansas-Nebraska Act of 1854 left the question of slavery to popular sovereignty, and both sides rushed to pack the territory with sympathetic settlers. Pro-slavery "Border Ruffians" from Missouri crossed into Kansas to stuff ballot boxes. The New England Emigrant Aid Company sent abolitionist settlers west. Two rival governments claimed authority. Violence had been escalating for months, but it remained scattered -- eight politically motivated killings in two years across the entire territory. The pro-slavery press was openly calling for extermination of abolitionist settlers. When the Douglas County Sheriff led his posse into Lawrence on May 21, Brown watched the anti-slavery response and found it cowardly. He decided to answer with a message no one could ignore.

Brown's party consisted of himself, four of his sons -- Frederick, Owen, Salmon, and Oliver -- along with Thomas Wiener and James Townsley, who drove the wagon. They hid in a ravine between two deep gullies until the evening of May 24, then set out after dark. Their first stop was the cabin of James P. Doyle. Brown ordered Doyle and his two adult sons, William and Drury, outside as prisoners. Doyle's wife pleaded for her 16-year-old son John, who was not a member of the pro-slavery Law and Order Party; the boy was spared. Owen and Frederick Brown killed the three Doyle men with broadswords in the darkness. The elder Brown fired a single shot into the head of the fallen James Doyle. The band then took Allen Wilkinson from his home and killed him. After midnight, they forced their way into the cabin of James Harris, interrogated his house guests about their pro-slavery activities, and led William Sherman to the edge of the creek, where he was hacked to death. Five men dead in a single night. Brown's primary target, a militant pro-slavery activist known as "Dutch Henry" Sherman, was away on the prairie.

The Pottawatomie massacre shattered whatever restraint had existed in Kansas Territory. William G. Cutler, writing in 1883, called it the "crowning horror" of the Bleeding Kansas period. In the three months that followed, retaliatory raids and battles claimed 29 more lives. The violence transformed John Brown from a marginal figure into a symbol -- hero to abolitionists, terrorist to pro-slavery forces. Frederick Douglass acknowledged the horror but placed it in context: "a terrible remedy for a terrible malady." Kansas Senator John James Ingalls, writing in 1884, judged Brown "the only man who comprehended the situation, and saw the absolute necessity for some such blow, and had the nerve to strike it." Brown himself remained evasive about his role, though it was no secret in Kansas. A congressional committee identified him as the chief perpetrator. His son Salmon, who had wielded one of the swords, called it "the grandest thing that was ever done in Kansas."

Pottawatomie Creek still winds through Franklin County, Kansas, through the same rolling prairie where Brown's party hid in their ravine. The landscape remains largely rural, much as it was in 1856. Three years after the massacre, Brown would lead his famous raid on Harpers Ferry, Virginia, and be hanged for treason -- an execution that further polarized the nation and helped ignite the Civil War. The debate over Brown's legacy endures. Was the Pottawatomie massacre a justified act of self-defense against a conspiracy to exterminate Free-State settlers? Or was it midnight assassination, as Kansas Governor Charles Robinson argued? Robinson noted that threats of violence were "as plenty as blue-berries in June, on both sides," and could hardly justify killing men in the dark. The creek offers no answer. It flows on, as it did that May night when five men were pulled from their beds and did not return.