US CIVIL WAR
The American Civil War, also known as the War Between the States or simply the Civil War (see naming), was a civil war fought from 1861 to 1865 in the United States after several Southern slave states declared their secession and formed the Confederate States of America (the "Confederacy" or the "South"). The states that remained were known as the "Union" or the "North". The war had its origin in the fractious issue of slavery, especially the extension of slavery into the western territories. Foreign powers did not intervene. After four years of bloody combat that left over 600,000 soldiers dead and destroyed much of the South's infrastructure, the Confederacy collapsed, slavery was abolished, and the difficult Reconstruction process of restoring national unity and guaranteeing rights to the freed slaves began.
Slavery in the United States for this article refers to the legal institution that existed in the United States of America in the 18th and 19th centuries. Slavery had been practiced in British North America from early colonial days, and was firmly established by the time of the United States' Declaration of Independence (1776). After this, there was a gradual spread of abolitionism in the North, while the rapid expansion of the cotton industry from 1800 caused the South to identify strongly with slavery, and attempt to extend it into the new Western territories. Thus slavery polarized the nation into slave states and free states along the Mason-Dixon Line, which separated Maryland (slave) and Pennsylvania (free).