Stephen Arnold Douglas (23 April 1813 – 3 June 1861) was an American politician from Illinois. He was a U.S. Representative, a U.S. Senator, and the Democratic Party nominee for President in the 1860 election, losing to Republican Abraham Lincoln. Douglas had previously defeated Lincoln in a Senate contest, noted for the famous Lincoln-Douglas debates of 1858. He was nicknamed the "Little Giant" because though short in physical stature, he was a forceful and even dominant figure in politics.

Douglas was well known as a resourceful party leader, and an adroit, ready, skillful tactician in debate and passage of legislation. He was a leading proponent of democracy, and believed in the principle of popular sovereignty: that the majority of citizens should decide contentious issues such as slavery and territorial expansion. As chairman of the Committee on Territories, Douglas dominated the Senate in the 1850s. He was largely responsible for the Compromise of 1850 that apparently settled slavery issues. However, in 1854 he reopened the slavery question with the Kansas–Nebraska Act, which opened some previously prohibited territories to slavery under popular sovereignty. Opposition to this led to the formation of the Republican Party.

Abraham Lincoln ⁱ/ˈeɪbrəhæm ˈlɪŋkən/ (February 12, 1809 – April 15, 1865) was the 16th President of the United States, serving from March 1861 until his assassination in April 1865. He successfully led his country through its greatest constitutional, military and moral crisis – the American Civil War – preserving the Union while ending slavery, and promoting economic and financial modernization. Reared in a poor family on the western frontier, Lincoln was mostly self-educated. He became a country lawyer, a Whig Party leader, Illinois state legislator in the 1830s, and a one-term member of the United States House of Representatives in the 1840s. After a series of debates in 1858 that gave national visibility to his opposition to the expansion of slavery, Lincoln lost a Senate race to his arch-rival Stephen A. Douglas. Lincoln, a moderate from a swing state, secured the Republican Party nomination. With almost no support in the South he swept the North and was elected president in 1860. His election was the signal for seven southern slave states to declare their secession from the Union and form the Confederate States of America. The departure of the Southerners gave Lincoln's party firm control of Congress, but no formula for compromise or reconciliation was found. And the war came.