Final answer:
The Know-Nothing and Free Soil parties emerged from the fall of the Whig Party and held stances against immigrant influence and the westward expansion of slavery, respectively. The Republican Party consolidated various anti-slavery factions, heightening sectional tensions that led to the Civil War. The divisive Election of 1856 and the fragmented Democratic Party during the Election of 1860 facilitated the ascent of the Republican Party and ultimately the secession of the Southern states.
Step-by-step explanation:
Analyzing the Contribution of Political Parties to the Breakup of the Union
The period leading up to the American Civil War saw significant political upheaval with the collapse of the second-party system. The Know-Nothing Party, emerging in response to increased immigration in the late 1840s and early 1850s, opposed the influence of immigrants and became one of several factions that the disintegrating Whig Party splintered into. The Free Soil Party objected to the westward expansion of slavery, focusing on how it would affect free, non-slaveholding whites and the future of the Union.
The Republican Party was formed by a coalition including anti-slavery activists, Free Soilers, and former Whigs. After the Kansas-Nebraska Act, the growing opposition to the expansion of slavery further accelerated the formation of the Republican Party, which unified various disparate groups that were discontent with the Democrats' control of the national government. Key events such as 'Bleeding Kansas' and Charles Sumner's assault by Preston Brooks intensified sectional tensions, and the Election of 1856 underscored these deep divisions, culminating in a stronger Republican presence in the North.
Entering the Election of 1860, the national debate over slavery was reaching a boiling point. The Democratic Party's fragmentation and the rise of a sectional Republican Party, which successfully captured the presidency with Abraham Lincoln, propelled the Southern states towards secession, as they perceived an existential threat to the institution of slavery. These developments significantly contributed to the breakup of the Union.