John Brown hoped to use the guns he seized at Harpers Ferry to give them to the enslaved to start rebellions.
Many Northerners, especially those who were anti-slavery, continued to engage in a sustained fight against slavery.
Popular sovereignty meant that local residents would decide whether territories were slave or free. Proponents were hopeful it would advance the plantation system and set the stage for slavery's expansion in newly formed territories.
John Brown's raid heightened proslavery sentiment because it demonstrated that abolitionists could and would resort to armed rebellion to end slavery.