The first of the Lincoln-Douglas debates took place in Ottawa, Illinois, featuring Republican candidate Abraham Lincoln and Democratic incumbent Stephen A. Douglas. Campaigning for the Illinois Senate seat, Lincoln and Douglas debated the pressing issue of slavery, specifically its expansion into newly acquired territories. The venue, Ottawa, was a neutral ground chosen to maximize accessibility for voters. Drawing large crowds, the debates were not just local spectacles but were representative of the national tensions surrounding the slavery question. Douglas, a well-established politician, advocated for popular sovereignty, which allowed territories to decide on the issue of slavery themselves, while Lincoln staunchly opposed the spread of slavery into the West, highlighting its moral issues. The format of the debates allowed each candidate to present his views and rebut the other's positions in an extended dialogue, a rarity in political contests of the time.

The debates were critical as they set the tone for the political discourse leading up to the 1860 presidential election. Lincoln’s articulate opposition to the extension of slavery gained him national recognition and revealed his capabilities as a leader in what was becoming an increasingly polarized American landscape. Although Douglas would win the Senate seat, the debates were a significant boost for Lincoln, positioning him as a national figure and laying the groundwork for his eventual presidential campaign.