It is now universally understood, if not conceded, that the Rebellion of 1861 was begun for the sole purpose of defending and preserving to the seceding States the institution of African slavery and making them the nucleus of a great slave empire, which in their ambitious dreams they hoped would include Mexico, Central America, and the West India Islands, and perhaps even the tropical States of South America. Both a real and a pretended fear that slavery was in danger lay at the bottom of this design. The real fear arose from the palpable fact, impossible to conceal, that the slave system was a reactionary obstacle in the pathway of modern civilization, and its political, material, philosophical, and religious development. The pretended danger was the permanent loss of political power by the slave States of the Union, as shown in the election of Lincoln to the presidency, which they averred would necessarily throw all the forces of the national life against the "peculiar institution," and crush it under forms of law. It was by magnifying this danger from remote into immediate consequence that they excited the population of the cotton States to resistance and rebellion. Seizing this opportunity, it was their present purpose to establish a slave Confederacy, consisting of the cotton States, which should in due time draw to itself, by an irresistible gravitation of sympathy and interest, first, the border slave States, and, in the further progress of events, the tropical countries towards the equator. The popular agitation, or war of words between the North and the South on the subject of slavery, which led to the armed insurrection was threefold: First, the economic efforts to prevent the destruction of the monetary value of four millions of human beings held in bondage, who were bought and sold as chattels, and whose aggregate valuation, under circumstances existing at the outbreak of the civil war, was variously computed at $400,000,000 to $1,600,000,000; [Footnote: The Convention of Mississippi, which passed the secession ordinance, in its Declaration of Causes placed the total value of their property in slaves at "four billions of money," This was at the rate of a thousand dollars for each slave, an average absurdly excessive, and showing their exaggerated estimate of the monetary value of the institution of slavery.] second, a moral debate as to the abstract righteousness or iniquity of the system; and, third, a political struggle for the balance of power in government and public policy, by which the security and perpetuity of the institution might be guaranteed.