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. Lincoln 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, and became a country lawyer, a Whig Party leader, Illinois state legislator during the 1830s, and a one-term member of the United States House of Representatives during 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, Lincoln 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 Confederacy. 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.