Manifest Destiny led to expansion west and many new states entering the Union. Expansion, as well as the issue over slavery, started when the U.S. conquered Mexico and annexed Texas as a slave state, against the Wilmot Proviso which was an act that never allowed slavery in any land captptured from Mexico, but it was never passed (Doc. B). The famous poet Ralph Waldo Emerson believed that the Union was killing itself by making the move of conquering Mexico and expanding (Doc. A). As a new state tried to enter the Union, whether it be free or slave, would tilt the balance of power in Congress one way or another which only strengthened the growing tension between North and South. Expansion led many Northerners to join the abolition movement. The Dred Scott case (said that slaves were property) and Anthony Burns incident (recapture of a slave in the north) led to thousands of citizens to speak out and protest against slavery (Doc. E and G). The abolitionist fire of the North was only strengthened by the book Uncle Tom's Cabin, showing the mistreatment of slaves in the South (Doc. I).
The government tried to appease both North and South through compromises such as the Missouri Compromise, Compromise of 1850 and the Kansas Nebraska Act. The Missouri Compromise evened the balance, letting both a free and slave state enter the Union at the same time, but the other two acts only added to the building pressure. In the Compromise of 1850, California was admitted as a free state while a stricter fugitive slave law was created. The fugitive slave law enraged many northerners