On the night of October 16th 1859 a party of 17 armed men led by the militant abolitionist John Brown crossed the Potomac River over the B&O railroad bridge to seize the federal arsenal at Harper's Ferry and its stockpile of 100,000 rifles and muskets. With these weapons, Brown intended to facilitate an armed slave uprising that would begin in Virginia and move South along the Blue Ridge as word of the revolt spread. The raid was initially successful. Brown's men seized the railroad bridge, rounded up the town's watchmen, cut the telegraph wire and seized the arsenal complex (guarded by a single sentry) without incident. It all went downhill from there.
Brown's entire plan hinged on the assumption that slaves in the surrounding countryside would flock to him after receiving word of the raid. However, no slaves were made aware of the planned attack, and consequently Brown quickly found himself surrounded in the morning not by eager runaway slaves but by angry townspeople and militia. Volleys were exchanged and hostages taken as Brown and his men retreated into the Arsenal's engine house (known today as John Brown's Fort) barricading themselves inside.
Meanwhile, An eastbound B&O train stopped by Brown's men earlier that morning was allowed to continue forward, whose conductor quickly wired a telegram reporting the raid to officials in Baltimore. In a matter of hours, Washington was alerted to the attack. President Buchanan dispatched a detachment of U.S. Marines led by Col. Robert E. Lee; future commander of the Confederate Army of Northern Virginia, to end the siege and capture John Brown. The Marines arrived in Harper's Ferry the next day. Brown refused to surrender himself in exchange for the lives of his remaining men, and the marines stormed the engine house to take Brown prisoner.