Final answer:
Frederick Douglass's impactful oratory and writings like his autobiography were key to the abolitionist movement, providing a deep personal account of slavery, inspiring abolitionists, and rallying international support for the cause.
Step-by-step explanation:
Frederick Douglass's speeches on slavery were integral to the abolitionist movement's success because they offered a powerful narrative and personal testimony to the cruelties of slavery. A skilled orator and accomplished writer, Douglass published his autobiography, Narrative of the Life of Frederick Douglass, an American Slave, which became a crucial piece of African American literature and a mobilizer for the abolitionist cause. His work provided a model of interracial coexistence, inspired weary abolitionists, and helped solidify international antislavery support networks, bolstering the push toward ending slavery.
Furthermore, his ability to articulate the complexities of slavery from the perspective of both the enslaved and the slaveholders showcased a sophisticated understanding that resonated with a wide audience. This, coupled with his efforts abroad to garner moral and financial support for the abolitionist movement, gave momentum to the cause and laid important groundwork for the eventual civil war that would end slavery in the United States.