Pro-slavery Border Ruffians , mostly from Missouri , illegally voted in a government . Pierce recognized this and called the Topeka Constitution , set up by Free-Staters , as an act of â rebellion . Pro-slavery Border Ruffians , mostly from Missouri , illegally voted in a government that Pierce recognized , and Pierce called the Topeka Constitution , a shadow government set up by Free-Staters , an act of `` rebellion . ''