What proposal, made by David Wilmot, aimed to ban slavery in new territories?

The proposal made by David Wilmot that aimed to ban slavery in new territories is the Wilmot Proviso. Introduced in 1846 during the debates over the Mexican-American War and the territories gained from it, this measure sought to prevent the expansion of slavery into any territory acquired from Mexico.

The significance of the Wilmot Proviso lies in its role as a catalyst for intense political debates over slavery, further polarizing the nation and contributing to the sectional conflict that eventually led to the Civil War. The proposal was never passed into law, but it sparked discussions that led to the emergence of the Free Soil Party and highlighted the deep divisions in American society regarding slavery and its expansion.

In contrast, other options reflect different historical attempts and compromises regarding slavery in American history. The Missouri Compromise was an earlier attempt to balance slave and free states, while the Kansas-Nebraska Act allowed territories to decide on the slave issue through popular sovereignty. The Fugitive Slave Act was a law requiring the return of escaped slaves but did not address the question of slavery in new territories. Thus, the Wilmot Proviso is distinctly recognized for its direct challenge to the expansion of slavery in newly acquired lands.