Thomas H.Benton, for thirty years a Senator from Missouri, and a national figure, was the storm-center.

His enemies accused him of being a Free-Boiler, an abolitionist in disguise.

He was professedly a stanch and uncompromising unionist, a personal and political opponent of John C.Calhoun.According to his own statement he had been opposed to the extension of slavery since 1804, although he had advocated the admission of Missouri with a pro-slavery constitution in 180.

He was, from the first, senior Senator from the State, and by a peculiar combination of influences incurred his first defeat for reelection in 1851.
Benton's defeat in the Missouri Legislature was largely the result of national pro-slavery influences.

In a former chapter, reference was made to the Ohio River as furnishing a "providential argument against slavery." The Mississippi River as the eastern boundary of Missouri furnished a like argument, but on the north not even a prairie brook separated free labor in Iowa from slave labor in Missouri.