Fields, Barbara Jeanne. Slavery and Freedom on the Middle Ground: Maryland during the Nineteenth Century. New Haven: Yale University Press, 1985.

Summary
-  This book examines the tense relationship between slave and free labor, black and white in Maryland leading up to and after the Civil War. The rise of two free populations in Maryland, one white and one black, “challenged the political, moral and ideological coherence of slave society.” The rise of a largely free labor society signaled a political threat to slaveholders. Yet, Fields warns, the presence of a larger, free black population should not be read as evidence as an inevitable transition from slavery to freedom. Freed blacks continued to be embedded within the slave system and had a limited status as freed blacks. She also shows that slavery was just as harsh and slaveholders defended slavery just as staunchly as their confederate counterparts, especially during the Civil War. Moreover, freed blacks cannot just be examined as an emerging proletariat, but as workers trying to find self-sufficiency through their independent pursuits. Maryland was thus an ideological and geographical middle ground that united conflicting economic interests between slaveholders and commercial elites. Commercial elites in Baltimore were still held politically subject to the land and slave-owning elite of Southern Maryland. This middle ground must be understood as an obligation, she contends, not as something ignoble or an enlightened philosophical outlook. She argues that civil war marked the end of slavery and thus the political middle ground. As a it result, it redefined the slaveholder and slave relationship, as well as the relationships between former free black and former slave, former slaveholder and former nonslaveholder, between city and country, and between government and citizen. The politics afterwards proved to be just as a difficult as in the confederacy.

Example: The presence of slavery continued to set close boundaries on liberty of the ostensibly free, and affected the social relations between slaves and free black people. For example, laws were established that could bound freed black children to “apprenticeships” and become personal property if they were not being taught in the “habits of industry”; freed blacks were also unable to own dogs or firearms, or purchase liquor with a special licenses; they could not sell bacon, pork, or grains without certification from a justice of peace. As these laws reflect, the continuity of the slave system defined and limited the status of free blacks (conscript slaves).

See also: Thomas Bender, Walter Johnson, Eric Foner