When the United States went to war with Mexico in 1846, the conflict was about the boundary dispute between the newly annexed state of Texas and Mexico. With the United States invading Mexican territory in the contested area, the Mexicans answered the invasion with violence and struck back. For two years, the two sides battled until Mexico had to accept defeat and surrendered large parts of its Northwestern Territory, which became the Mexican Cession. The discovery of Gold in California created a massive influx of settlers and brought the request for admission as a free state. The request opened a deep division within the United States. California’s entry as a free state would permanently place a limit on the extend slave territory could go; in conjunction with the Missouri Compromise, southern slaveholders perceived the geographical limitations would soon spell the end of slavery.

All the great political minds of the previous generation, John C. Calhoun, Daniel Webster, Edward Everett, and Henry Clay, as well as the new generations, Stephen Douglas and William H. Seward were in the Senate in 1849/1850 when the debate over admission of California started. With sectional tensions at an all time high, Congress failed to pass Henry Clay’s five part compromise proposal. Broken into pieces, Stephen Douglas was able to get majorities to approve the admission of California as a free states, leave the slavery question in Utah and New Mexico territory open to the settlers, end the slave trade in the District of Columbia, pass a stronger fugitive slave law, and deal with the territory and debt of Texas. However, the debate had indicated that slavery in the western territories, where it did not exist yet, would be the political conflict point for the next decade.

Image: Peter F. Rothermel / engraved by Robert Whitechurch, United States Senate, A.D. 1850, Philadelphia, PA: John M. Butler and Alfred Long, c1855.