The first state to split from the U.S. was South Carolina, and its declaration of secession details "the immediate causes which have led to this act," all of which pertain to slavery. Likewise, the secession declarations of Georgia, Mississippi, and Texas all identify slavery as their main reason for splitting from the U.S. Furthermore, the vice president of the Confederacy, Alexander Stephens, stated that "African slavery" is "the proper status of the negro in our form of civilization" and "was the immediate cause of the late rupture and present revolution." However, a very popular book by Howard Zinn titled "A People's History of the United States" portrays Lincoln and other opponents of slavery as driven by greed instead of principle, and it claims that the Civil War was mainly caused by class resentments. The primary sources of the Civil War era, which are quoted above and documented at the first link below, disprove Zinn's historical revisionism.