Arguably Joseph Smith’s most famous prophecy relates to the American Civil War. Paul H. Peterson comments:
Joseph Smith’s Civil War prophecy is contained in sections 87 and 130 of the Doctrine and Covenants. He prophesied on December 25, 1832, that a war would begin in South Carolina; that the southern states would divide against the northern states; that the South would seek support from other nations, including Great Britain; and that the war would lead to the death and misery of many souls. These items in the prophecy were all fulfilled in the Civil War (1860-1865). In 1843 the Prophet noted (D&C 130:12-13) that he had also learned by revelation in 1832 that slavery would be the probable cause of the upcoming crisis. These matters are all history now, but certain verses in the Civil War prophecy have broader applications and it appears that portions of the revelation are yet to be fulfilled.
Section 87 was not published by the Church until 1851 and was not canonized until 1876. It was, however, copied and circulated by some Church leaders and missionaries in the 1830s. The Civil War prophecy became one of the most widely published revelations in the Doctrine and Covenants. Not surprisingly, it received greatest attention during the Civil War, as many viewed the conflict as a vindication of the prophetic powers of Joseph Smith.– Paul H. Peterson – Civil war prophecy
How did Joseph Smith know in advance about the civil war? How did he know such specific details about it?