Abraham Lincoln won the 1860 presidential election as an opponent of the extension of slavery into the U.S. territories. His victory triggered declarations of secession by seven slave states of the Deep South, all of whose riverfront or coastal economies were based on cotton that was cultivated by slave labor. They formed the Confederate States of America after Lincoln was elected in November 1860 but before he took office in March 1861. Nationalists in the North and "Unionists" in the South refused to accept the declarations of secession. No foreign government ever recognized the Confederacy. The refusal of the U.S. government, under President James Buchanan, to relinquish its forts that were in territory claimed by the Confederacy, proved to be a major turning point leading to war. The war itself began on April 12, 1861, when Confederate forces bombarded the Union's Fort Sumter, in the harbor of Charleston, South Carolina.