Final answer:
The crisis of slavery in the territories reached a boiling point after the Mexican-American War, particularly with the question of California's admission as a free state and the Compromise of 1850, before ultimately contributing to the secession of Southern states and the Civil War.
Step-by-step explanation:
The Crisis of Slavery in the Territories
The issue of slavery in the territories came to a head in the mid-19th century, particularly after the Mexican-American War which resulted in the acquisition of new territories. The central question was whether slavery should be allowed in these newly acquired lands. This debate was sparked by the 1846 wartime proposal known as the Wilmot Proviso, which sought to prohibit slavery in any territory gained from Mexico, though it was never passed into law.
The situation intensified with the application of California to enter the Union as a free state in 1849, leading to a serious imbalance in the balance of power between free and slave states. This, combined with other events such as the Fugitive Slave Act, Kansas-Nebraska Act, Dred Scott decision, and ultimately Abraham Lincoln's election, escalated sectional tensions to breaking point and ultimately led to the secession of the Southern states, paving the way for the Civil War.
The Compromise of 1850 attempted to address these issues by admitting California as a free state and enacting other measures, but it was only a temporary solution. Sectional strife continued to grow, as seen in the violence of 'Bleeding Kansas' and the political upheaval leading up to the Civil War.