In October 1859 John Brown and other antislavery men slipped across the border between Maryland and Virginia and occupied the United States arsenal at Harpers Ferry. Brown hoped to arm enslaved men and lead a campaign to abolish slavery. He failed, and Colonel Robert E. Lee in command of a company of United States Marines and with some assistance from local militia units captured Brown and killed or captured most of his followers. Brown was tried and convicted of treason against Virginia. The state's governor, Henry A. Wise, refused pleas to treat Brown leniently and allowed him to be hanged on December 2, 1859.
Sectional tensions about slavery and John Brown's Raid on Harpers Ferry inflamed public opinion. Many Southern slave owners feared that other abolitionists would also incite an insurrection of enslaved people and spread violence and bloodshed throughout the South. The suspicions and distrust between the political leaders and citizens of the free states and of the slave states had increased during the decade and Brown's Raid made the solution of political differences even more difficult. The 1850s ended with the future of the Union in doubt.