<P> The American Civil War (commonly known as the "Civil War" in the United States) was fought in the United States from 1861 to 1865 . The result of a long - standing controversy over slavery, war broke out in April 1861, when Confederates attacked Fort Sumter in South Carolina, shortly after Abraham Lincoln was inaugurated . The nationalists of the Union proclaimed loyalty to the U.S. Constitution . They faced secessionists of the Confederate States of America, who advocated for states' rights to perpetual slavery and its expansion in the Americas . </P> <P> Among the 34 U.S. states in February 1861, seven Southern slave states individually declared their secession from the U.S. to form the Confederate States of America . The Confederacy grew to include eleven states; it claimed two more border states (Kentucky and Missouri), the Indian Territory, and the southern portions of the Union's western territories of Arizona and New Mexico, which was organized and incorporated into the Confederacy as Confederate Arizona . The Confederacy was never diplomatically recognized by the United States government, nor was it recognized by any foreign country (although Britain and France granted it belligerent status). The states that remained loyal, including the border states where slavery was legal, were known as the Union or the North . </P> <P> The North and South quickly raised volunteer and conscription armies that fought mostly in the South over four years . During this time many innovations in warfare occurred, including the development and use of iron - clad ships, ultimately changing naval strategy around the world . The Union finally won the war when General Robert E. Lee surrendered to General Ulysses S. Grant at the battle of Appomattox, which triggered a series of surrenders by Confederate generals throughout the southern states . Four years of intense combat left 620,000 to 750,000 soldiers dead, a higher number than the number of American military deaths in both World Wars, Korea, Vietnam, Iraq and Afghanistan combined, and much of the South's infrastructure was destroyed . The Confederacy collapsed, slavery was abolished, and 4 million slaves were freed . The Reconstruction Era (1863--1877) overlapped and followed the war, with the process of restoring national unity, strengthening the national government, and granting civil rights to freed slaves throughout the country . The Civil War is arguably the most studied and written about episode in American history . </P> <P> In the 1860 presidential election, Republicans, led by Abraham Lincoln, supported banning slavery in all the U.S. territories . The Southern states viewed this as a violation of their constitutional rights and as the first step in a plan to eventually abolish slavery . The three pro-Union candidates together received an overwhelming 82% majority of the votes cast nationally: Republican Lincoln's votes centered in the north, Democrat Stephen A. Douglas' votes were distributed nationally and Constitutional Unionist John Bell's votes centered in Tennessee, Kentucky, and Virginia . The Republican Party, dominant in the North, secured a plurality of the popular votes and a majority of the electoral votes nationally, so Lincoln was constitutionally elected president . He was the first Republican Party candidate to win the presidency . However, before his inauguration, seven slave states with cotton - based economies declared secession and formed the Confederacy . The first six to declare secession had the highest proportions of slaves in their populations, a total of 49 percent . The first seven with state legislatures to resolve for secession included split majorities for unionists Douglas and Bell in Georgia with 51% and Louisiana with 55% . Alabama had voted 46% for those unionists, Mississippi with 40%, Florida with 38%, Texas with 25%, and South Carolina cast Electoral College votes without a popular vote for president . Of these, only Texas held a referendum on secession . </P>

Who won the civil war union or confederate