Decades of controversy over slavery came to a head when Abraham Lincoln, who opposed slavery's expansion, won the 1860 presidential election. Seven Southern slave states responded to Lincoln's victory by seceding from the United States and forming the Confederacy. The Confederacy seized US forts and other federal assets within its borders. The war began on April 12, 1861, when the Confederacy bombarded Fort Sumter in South Carolina. A wave of enthusiasm for war swept over the North and South, as military recruitment soared. Four more Southern states seceded after the war began and, led by its president, Jefferson Davis, the Confederacy asserted control over a third of the US population in eleven states. Four years of intense combat, mostly in the South, ensued.