Douglas opposed John Brown's plan to raid at the Harper's ferry because he was sure that the plan would fail and there would be many black deaths.
Explanation:
John Brown was an extreme abolitionist whose intense scorn of subjection drove him to hold onto the United States arms stockpile at Harper's Ferry in October 1859. Hanged for treachery against the Commonwealth of Virginia, Brown immediately turned into a saint among those looking to end subjugation in America.
Douglas denounced servitude in look and language furious and harsh, imagined that slaveholders had relinquished their entitlement to live, that the slaves reserved the option to pick up their freedom in any capacity they could, didn't accept that ethical suasion could ever free the slave, or that political activity would cancel the framework.