Final answer:
James Buchanan attempted to keep the Union together by supporting the pro-slavery Dred Scott decision, advocating popular sovereignty, and promoting the Lecompton Constitution for Kansas. These actions only escalated tensions, leading closer to secession and the Civil War.
Step-by-step explanation:
James Buchanan's Efforts to Preserve the Union
President James Buchanan's attempts to keep the Union together were marked by his support for the Dred Scott decision. This 1857 Supreme Court ruling stated that black Americans could not be considered citizens and supported the extension of slavery. Buchanan believed that this decision would settle the sectional conflicts over slavery but it instead increased tensions between the North and South. He advocated for the concept of popular sovereignty in territories, suggesting that residents should decide the issue of slavery. However, his inability to strongly address the crisis in Kansas, where violence broke out over slavery, showed the limitations of this approach. Notably, Buchanan also pushed for the consideration of the Lecompton Constitution which was a pro-slavery proposal for Kansas' statehood, further alienating the anti-slavery North.