Final answer:
John Brown was a radical abolitionist who planned an insurrection to end slavery through a raid on Harpers Ferry. Despite his failed attempt, his composure during his trial and execution transformed public opinion.
Step-by-step explanation:
John Brown was a radical abolitionist who advocated for the violent overthrow of slavery. He believed that the only way to end slavery was through armed rebellion. Brown planned an insurrection and executed a raid on Harpers Ferry in 1859, with the goal of capturing weapons and distributing them among enslaved people to start a massive uprising against slavery. However, his plan failed and he was captured by federal troops and hanged. Despite the majority of northerners criticizing his raid, Brown's composure during his trial and facing execution transformed public opinion, with many considering him a martyr to the abolitionist cause.