Inveterate imperialists: contested imperialisms, North American history, and the coming of the U.S. Civil War

In the decades preceding the U.S. Civil War, sectional conflict frequently took place in overlapping continental, hemispheric, Atlantic, and international contexts. Within these broader geographies, northern and southern whites used conceptions of empire to construct a hemispheric, Manichean struggle pitting free labour versus slave labour, democracy against aristocracy and monarchy, and popular sovereignty versus slaveholder sovereignty and the Slave Power. Beginning in the 1840s, and deepening in the 1850s, southern whites forged an imperial ideology which called for the creation of a vast empire for slavery in the Americas. Responding directly to the rise of southern pro-slavery imperialism, northern whites created an imperial ideology based on democratic-republican forms of government and free labour. By the late 1850s, Democratic and Republican imperialists advocated the imposition of their particular forms of sovereignty, race, labour, and republican government onto their sectional rivals as well as onto borderland regions in the trans-Mississippi West, Mexico, the Caribbean, and Central America. In the 1850s the United States became an empire increasingly divided by antagonistic imperial visions for the broader Americas; by 1860, Democrats and Republicans had become de facto imperial rivals.