Lincoln is also admired because of his leadership during the difficult period of the Civil War. He dared to do what he thought was right at a time when his beliefs were unpopular with many people. He, in a sense, represents the spirit of union among the states. Before the Civil War, the economy of the South depended on an agricultural system which made use of slave labor. When reformers （改革家）in the northern states put pressure on Congress not to permit slavery in western territories that later became states, some of the southern states wanted to secede, or withdraw, from the United States. They argued that the question of slavery was a matter for the individual states to decide rather than the federal government, and they did not want to accept its decision. The national government said that no state had the right to secede, and the Civil War was the result. If the South had won the war, what is now the United States might well have been divided into several countries. Lincoln worked hard to preserve the union, and the northern states were victorious.