The 1848 treaty with Mexico did not bring the United States domestic peace. Instead, the acquisition of new territory revived and intensified the debate over the future of slavery in the western territories, widening the growing division between North and South and leading to the creation of new single-issue parties. Increasingly, the South came to regard itself as under attack by radical northern abolitionists, and many northerners began to speak ominously of a southern drive to dominate American politics for the purpose of protecting slaveholders’ human property. As tensions mounted and both sides hurled accusations, national unity frayed. Compromise became nearly impossible and antagonistic sectional rivalries replaced the idea of a unified, democratic republic.