stuff the ballot-box(es)

Would you tell me whether I am right with my interpretation of the expression in bold in the following sentence?

Tillman raged openly on the floor of congress: “Yes, we have stuffed ballot-boxen, and will stuff them again…” (W. Du Bols, “The Ordeal of Mansart”)

stuff the ballot-box(es) = falsify the ballot

Thanks for your efforts.

Yes, by putting in extra, falsified votes.