He served as delegate to the convention held in Washington, D.C., in 1861 in an effort to devise means to prevent the impending war.

He moved to St. Charles, Missouri, in 1862 and became interested in the manufacture of tobacco in St. Louis.

[1] While many congressmen of that era held racist views, Buckner was a particularly strong advocate of the racial supremacy of whites.

While enthusiastically advocating for restrictions on Chinese immigration, he also called for the removal of African Americans from the United States, asking "what reason can be assigned that we do not prepare to remove, not by forced expatriation or by any form of coercion, that portion of our population that, like the Chinese, are aliens to our race, whose blood does not mingle with that of the white race without corrupting it, and whose inferiority to the white race is an admitted fact?

"[2] While other congressmen were critical of granting rights to African Americans, even most southern members did not go so far as to advocate that millions of citizens be removed from the country.