American Civil War, was a four-year war (1861–65) between the federal government of the United States and 11 Southern states that asserted their right to secede from the Union.
The secession of the Southern states in 1860–61 and the ensuing outbreak of armed hostilities were the culmination of decades of growing sectional friction over the related issues of slavery, trade and tariffs, and the doctrine of states’ rights. This friction arose out of fundamental differences between the economies of the Northern and Southern states. The North had a growing manufacturing sector and small farms using free labour, while the South’s economy was based on large farms (plantations) using slave labour. In the 1840s and ’50s the Northern states wanted to prohibit slavery in the western territories that would eventually become new states. The Southern states opposed all efforts to block the expansion of slavery and feared that the North’s stance would eventually endanger existing slaveholdings in the South itself. By the 1850s, some Northerners had begun calling for the complete abolition of slavery, while several Southern states threatened to secede from the Union as a means to protect their right to keep slaves. When Abraham Lincoln, the candidate of the antislavery Republican Party, was elected president in late 1860, the Southern states carried out their threat and seceded, organizing as the Confederate States of America.
At first glance it seemed that the 23 states of the Union were more than a match for the 11 seceding Southern states. There were approximately 21 million people in the North compared with some 9 million in the South. In addition, the Federals possessed over 100,000 manufacturing plants as against 18,000 south of the Potomac River, and more than 70 percent of the railroads were in the North. Furthermore, the Union had at its command a 30-to-1 superiority in arms production, a 2-to-1 edge in available