The American Civil War was primarily about slavery, although other factors such as states' rights and economic development also played a role. The war began in 1861 when seven southern states seceded from the Union after Abraham Lincoln was elected president. The southern states were primarily agricultural and relied heavily on slavery for their labor force. They feared that Lincoln, who was a member of the anti-slavery Republican Party, would abolish slavery and threaten their way of life. The northern states were primarily industrial and did not rely on slavery. They believed that the southern states had no right to secede from the Union and that slavery should be abolished. The war ended in 1865 with the defeat of the Confederate States of America and the abolition of slavery.