In many abolitionist circles, there was concern that a small number of Southern slaveholders were already dominating the national political landscape. Many Whigs pointed to the Mexican War as evidence of this, a war launched by a slaveholder to potentially increase the amount of land available for slavery. It did not help that Southern congressmen hatched a plan to buy Cuba from Spain in order to make another slave state. Northerners feared that slavery would make it impossible for free labor to compete in the West and in U.S. industries. Other groups wanted slavery to end because it was in line with American values of liberty.
Southern slaveholders viewed the slaves as necessary to maintaining the cotton kingdom. They pointed out that the Northeast as well as world markets were dependent on Southern cotton for the textile industry. They also pointed out that the Constitution protected private property and it was impossible for the federal government to pay fair market prices in order to emancipate the slaves since the nation's slaves were worth more than all the railroads and banks in the U.S. put together before 1860. Southerners tried to claim that they were "civilizing" the African slaves by teaching them Western ways and Christianity. They also pointed out the unclear status of what would become of the slaves if freed. Southern plantation owners feared a national slave revolt that would topple white society.
Each side believed that its side was correct and the other one was trying to destroy the country. One could see signs of the debate's failure in Bleeding Kansas and the Harper Ferry's attack in 1859. Lincoln had no plans to end slavery; rather, he hoped to limit it to where it already existed. Southerners did not want anything to do with a party that had any association with moderates or abolitionists, so after Lincoln's election they seceded, starting with South Carolina in December 1860.