The invasion of Kansas by the Border Ruffians occurred as tensions escalated between pro-slavery and anti-slavery settlers in the region. Following the passage of the Kansas-Nebraska Act in 1854, which allowed the settlers of Kansas and Nebraska to determine the status of slavery through popular sovereignty, many from the surrounding slave-holding states, particularly Missouri, sought to influence the political outcomes in Kansas. Armed groups known as Border Ruffians ventured across the state line, aiming to elect a pro-slavery legislature. The influx of these individuals was characterized by violent tactics, including intimidation and voter suppression aimed at those who opposed slavery. Their objective was clear: to ensure that the new territory would adopt pro-slavery laws and align with Southern interests.

As the elections approached in March 1855, the presence of these armed men created an atmosphere of fear and uncertainty. Local anti-slavery inhabitants were outnumbered and faced numerous threats, leading to significant challenges for those determined to vote against slavery. The pro-slavery faction won a majority, largely due to the actions of the Border Ruffians, who influenced the election results through coercive measures. This political maneuvering not only skewed the legislative balance in Kansas but also triggered violent confrontations known as 'Bleeding Kansas,' which erupted in the years to follow, as both sides vied for control of the territory.

The incursion of the Border Ruffians highlighted the national tension around the issue of slavery and set a precedent for violent conflict in the struggle over its expansion. This early chapter in the lead-up to the American Civil War marked a significant moment in American history, demonstrating how local actions could impact national debates over slavery and state rights. The unrest in Kansas ultimately contributed to broader national divisions and violence leading up to the Civil War.