Keeping in mind how the expansion of U.S. territory westward threatened the delicate balance of power in congress between free and slave states and Lincoln's stance on slavery, describe how key events (such as land acquisitions, agreements about how new territories should enter the union as states, etc.) led the country into the civil war.

The expansion of U.S. territory westward played a significant role in threatening the balance of power between free and slave states, ultimately leading to the Civil War. To understand how this occurred, it is essential to examine key events such as land acquisitions and agreements regarding the admission of new territories as states.

1. Manifest Destiny and Land Acquisitions: The concept of Manifest Destiny fueled the American desire to expand westward, claiming new territories and fulfilling a perceived destiny to spread democracy and civilization. The Louisiana Purchase in 1803, which doubled the size of the United States, and the later acquisitions of Florida, Texas, Oregon, and the Mexican Cession further increased the nation's territory.

2. Missouri Compromise (1820): As new territories sought statehood, the question of whether they would be free or slave states became contentious. The Missouri Compromise aimed to maintain sectional balance by admitting Missouri as a slave state and Maine as a free state, thus preserving the balance of power in Congress.

3. Sectional Differences and the Wilmot Proviso (1846): The issue of slavery became increasingly polarized, with northerners opposing its expansion into new territories. The Wilmot Proviso, introduced in 1846, proposed that slavery be prohibited in any territory acquired from Mexico. Although the proviso failed to pass, it highlighted the growing conflict and deepening divide between the North and South.

4. Compromise of 1850: California's request for statehood further exacerbated tensions. The Compromise of 1850 aimed to maintain equilibrium by admitting California as a free state, while allowing the inhabitants of other territories gained from Mexico to decide the slavery question (popular sovereignty). Additionally, the Fugitive Slave Act strengthened the power of southern slaveholders and intensified opposition in the North.

5. Kansas-Nebraska Act (1854): To facilitate the construction of a transcontinental railroad, the Kansas and Nebraska territories were organized, allowing popular sovereignty to determine the slavery issue. This act repealed the Missouri Compromise's restriction on slavery in territories north of the 36°30' line, inciting fierce clashes between pro-slavery and anti-slavery settlers in "Bleeding Kansas."

6. Dred Scott Case (1857): The Supreme Court's decision in the Dred Scott case heightened tensions. The court ruled that African Americans, regardless of being enslaved or free, were not U.S. citizens and could not sue in federal court. The decision further declared that Congress could not prohibit slavery in any territory, effectively invalidating the concept of popular sovereignty.

7. Election of Abraham Lincoln (1860): Lincoln, an opponent of the expansion of slavery, won the presidency in a highly contentious election. His election alarmed many southerners, as they believed he would threaten their rights. Several southern states subsequently seceded from the Union, forming the Confederacy.

In summary, the westward expansion of U.S. territory through land acquisitions, combined with disagreements over how new territories should enter the Union and the intensifying tensions over slavery, eventually led to the outbreak of the Civil War. The delicate balance of power between free and slave states was further undermined, and efforts to negotiate compromises failed as sectionalism and deeply ingrained differences reached a critical point.