<P> The primary catalyst for secession was slavery, especially Southern political leaders' resistance to attempts by Northern antislavery political forces to block the expansion of slavery into the western territories . Another explanation for secession, and the subsequent formation of the Confederacy, was white Southern nationalism . The primary reason for the North to reject secession was to preserve the Union, a cause based on American nationalism . Most of the debate is about the first question, as to why some southern states decided to secede . </P> <P> Abraham Lincoln won the 1860 presidential election without being on the ballot in ten Southern states . His victory triggered declarations of secession by seven slave states of the Deep South, whose riverfront or coastal economies were all based on cotton cultivated using slave labor . They formed the Confederate States of America after Lincoln was elected, but before he took office . Nationalists (in the North and "Unionists" in the South) refused to recognize the declarations of secession . No foreign country's government ever recognized the Confederacy . The U.S. government under President James Buchanan refused to relinquish its forts that were in territory claimed by the Confederacy . The war itself began on April 12, 1861, when Confederate forces bombarded Fort Sumter, a major U.S. fortress in the harbor of Charleston, South Carolina . </P> <P> As a panel of historians emphasized in 2011, "while slavery and its various and multifaceted discontents were the primary cause of disunion, it was disunion itself that sparked the war ." Pulitzer Prize winning author David Potter wrote, "The problem for Americans who, in the age of Lincoln, wanted slaves to be free was not simply that southerners wanted the opposite, but that they themselves cherished a conflicting value: they wanted the Constitution, which protected slavery, to be honored, and the Union, which had fellowship with slaveholders, to be preserved . Thus they were committed to values that could not logically be reconciled ." Other important factors were partisan politics, abolitionism, nullification vs secession, Southern nationalism, Northern nationalism, expansionism, economics and modernization in the Antebellum period . </P> <P> The United States had become a nation of two distinct regions . The free states in New England, the Northeast, and the Midwest had a rapidly growing economy based on family farms, industry, mining, commerce and transportation, with a large and rapidly growing urban population . Their growth was fed by a high birth rate and large numbers of European immigrants, especially British, Irish and Germans . The South was dominated by a settled plantation system based on slavery; there was some rapid growth taking place in the Southwest (e.g., Texas), based on high birth rates and high migration from the Southeast, but it had a much lower immigration rate from Europe . The heavily rural South had few cities of any size, and little manufacturing except in border areas . Slave owners controlled politics and the economy, although about 75% of white Southern families owned no slaves and usually were engaged in subsistence agriculture . </P>

What was the reason for us civil war
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