As a Senator, Atchison was a fervent advocate of slavery and territorial expansion. He supported the annexation of
Texas and the
U.S.-Mexican War. Atchison and Missouri's other Senator, the venerable
Thomas Hart Benton, became rivals and finally enemies, though both were Democrats. Benton declared himself to be against slavery in 1849, and in 1851 Atchison allied with the
Whigs to defeat Benton for re-election.
Benton, intending to challenge Atchison in 1854, began to agitate for
territorial organization of the area west of Missouri (now the states of
Kansas and
Nebraska) so it could be opened to settlement. To counter this, Atchison proposed that the area be organized
and that the section of the
Missouri Compromise banning slavery there be repealed in favor of
popular sovereignty, under which the settlers in each territory would decide themselves whether slavery would be allowed.
At Atchison's request,
Senator Stephen Douglas of
Illinois introduced the
Kansas-Nebraska Act, which embodied this idea, in November 1853. The Act became law on in May 1854, establishing the Territories of Kansas and Nebraska.
Border Ruffians
Douglas (and Atchison) had assumed that Nebraska would be settled by
Free-State men from
Iowa and
Illinois, and Kansas by pro-slavery Missourians and other Southerners, thus preserving the numerical balance between free states and slave states. In 1854 Atchison helped found the town of
Atchison, Kansas as a pro-slavery settlement. The town (and county) were named for him.
[1]
In fact, while Southerners welcomed the opportunity to settle Kansas, very few actually chose to do so. Instead, most free-soilers preferred Kansas. Furthermore, anti-slavery activists throughout the North came to view Kansas as a battleground and formed societies to encourage free-soil settlers to go to Kansas and ensure that both Kansas and Nebraska would become free states.
[2]
It appeared as if the Kansas Territorial legislature to be elected in March 1855 would be controlled by free-soilers and ban slavery. This was viewed as a breach of faith by Atchison and his supporters. An angry Atchison called on pro-slavery Missourians to uphold slavery by force and "to kill every God-damned
abolitionist in the district" if necessary.
[3] He recruited an immense mob of heavily armed Missourians, the infamous "
Border Ruffians". On the election day,
March 30,
1855, Atchison led 5,000 Border Ruffians into Kansas. They seized control of all polling places at gunpoint, cast tens of thousands of fraudulent votes for pro-slavery candidates, and "elected" a pro-slavery legislature.
[2]