Perhaps no decade in the history of the United States has been so filled with tense and crucial moments as the ten years leading to the Civil War, and closely connected with the majority of these crises was the problem of slavery,” writes Robert William Fogel in his book Without Consent or Contract: The Rise and Fall of American Slavery. In the 1850s, the divisive debate over slavery came to a climax as it became entwined with a variety of different events and social forces.

The discovery of gold in California and the acquisition of new southwestern territories after the Mexican War in 1848 greatly spurred the westward movement. Slaveholding and abolitionist interests deadlocked over the question of whether slavery should be permitted in the new territories. The result was the Compromise of 1850, under which California was admitted as a free state; the...