John Brown leads a raid on Harpers Ferry, West Virginia.

John Brown's raid on Harpers Ferry was an effort by abolitionist John Brown, from October 16 to 18, 1859, to initiate a slave revolt in Southern states by taking over the United States arsenal at Harpers Ferry, Virginia (since 1863, West Virginia). It has been called the dress rehearsal for, or Tragic Prelude to the Civil War.:5Brown's party of 22 was defeated by a company of U.S. Marines, led by First Lieutenant Israel Greene. Ten of the raiders were killed during the raid, seven were tried and executed afterwards, and five escaped. Several of those present at the raid would later be involved in the Civil War: Colonel Robert E. Lee was in overall command of the operation to retake the arsenal. Stonewall Jackson and Jeb Stuart were among the troops guarding the arrested Brown,:5 and John Wilkes Booth was a spectator at Brown's execution. Walt Whitman projected his poetic I as a silent spectator in his poem "Year of Meteors," although he was not actually present. John Brown had originally asked Harriet Tubman and Frederick Douglass, both of whom he had met in his transformative years as an abolitionist in Springfield, Massachusetts, to join him in his raid, but Tubman was prevented by illness and Douglass declined, as he believed Brown's plan was suicidal.The raid caused more excitement in the United States than had been seen in many years. It was extensively covered in the press nationwideit was the first such national crisis to be publicized using the new electrical telegraph. Reporters were on the first train leaving for Harpers Ferry after news of the raid was received, at 4 p.m. on Monday, October 17. It carried Maryland militia, and parked on the Maryland side of the Harpers Ferry bridge, just 3 miles (4.8 km) east of the town (at the hamlet of Sandy Hook, Maryland). As there were few official messages to send or receive, the telegraph carried on the next train, connected to the cut telegraph wires, was "given up to reporters", who "are in force strong as military".:17 By Tuesday morning the telegraph line had been repaired,:21 and there were reporters from The New York Times "and other distant papers".:23The label "raid" was not used at the time. A month after the attack, a Baltimore newspaper listed 26 terms used, including "insurrection", "rebellion", "treason", and "crusade". "Raid" was not among them.:4Brown's raid was at first viewed as madness, the work of a fanatic. It was his words and letters after the raid and at his trial, Virginia v. John Brown, aided by the writings of supporters including Henry David Thoreau, that turned him into a hero and icon for the Union.

John Brown (May 9, 1800 – December 2, 1859) was an American abolitionist leader. First reaching national prominence for his radical abolitionism and fighting in Bleeding Kansas, he was eventually captured and executed for a failed incitement of a slave rebellion at Harpers Ferry preceding the American Civil War. A man of strong religious convictions, Brown believed he was "an instrument of God",: 248  raised up to strike the death blow to American slavery, a "sacred obligation".: 189  Brown was the leading exponent of violence in the American abolitionist movement:: 426  he believed that violence was necessary to end American slavery, since decades of peaceful efforts had failed. Brown said repeatedly that in working to free the enslaved he was following the Golden Rule, as well as the U.S. Declaration of Independence, which states that "all men are created equal".: 721  He also stated often that in his view, these two principles "meant the same thing".Brown first gained national attention when he led anti-slavery volunteers and his own sons during the Bleeding Kansas crisis of the late 1850s, a state-level civil war over whether Kansas would enter the Union as a slave state or a free state. He was dissatisfied with abolitionist pacifism, saying of pacifists, "These men are all talk. What we need is action – action!". In May 1856, Brown and his sons killed five supporters of slavery in the Pottawatomie massacre, a response to the sacking of Lawrence by pro-slavery forces. Brown then commanded anti-slavery forces at the Battle of Black Jack and the Battle of Osawatomie.

In October 1859, Brown led a raid on the federal armory at Harpers Ferry, Virginia (today West Virginia), intending to start a slave liberation movement that would spread south; he had prepared a Provisional Constitution for the revised, slavery-free United States he hoped to bring about. He seized the armory, but seven people were killed, and ten or more were injured. Brown intended to arm slaves with weapons from the armory, but only a few slaves joined his revolt. Those of Brown's men who had not fled were killed or captured by local militia and U.S. Marines, the latter led by Robert E. Lee. Brown was tried for treason against the Commonwealth of Virginia, the murder of five men, and inciting a slave insurrection. He was found guilty of all counts and was hanged on December 2, 1859, the first person executed for treason in the history of the United States.: 179 The Harpers Ferry raid and Brown's trial, both covered extensively in national newspapers, escalated tensions that led, a year later, to the South's long-threatened secession and the American Civil War. Southerners feared that others would soon follow in Brown's footsteps, encouraging and arming slave rebellions. He was a hero and icon in the North. Union soldiers marched to the new song "John Brown's Body", that portrayed him as a heroic martyr. Brown has been variously described as a heroic martyr and visionary, and as a madman and terrorist.