The darkest hour for the anti-slavery cause preceded the dawn of 1854. The compromises of 1850 had closed that long series of so-called bargains, by which the South had forced surrender after surrender from the North in the vain hope of preserving by such artificial devices its traditional preponderance in the government, so constantly threatened by the rapid development of the free States and the marvelous settlement of free territory. Behind the Louisiana purchase from Bonaparte was slavery's demand for new States to reinforce its political strength. Florida was bought from Spain for the same reasons. The Missouri compromise of 1820 involved the admission of a new slave State to the Union, and the organization of Arkansas as a slave territory; it was the work of the advocates of slavery extension, and was practically a surrender of free territory to bondage, the only consideration being the exclusion of slavery from soil on which (judging from all the experience of American settlement up to that time) it could not be established nor maintained. The annexation of Texas had been forced to add to the Union an enormous expanse of slave territory, capable, it was hoped, of early division into several slave States. The Mexican War was a peculiarly Southern scheme, having as its real aim the conquest of an empire which was to include human bondage among its established institutions. The futile plans for the annexation of Cuba came from the same prolific source, and were inspired by the same need of forcing the expansion of the political power of the slave South to prevent its being outstripped by the magnificent growth of the free North. But the forces of nature prove more potent than human devices, and the last speech of John C. Calhoun (read for him in the Senate on March 4, 1850,) showed how clearly this fact had impressed itself on the ablest and acutest of the Southern statesmen. That farewell address sketched minutely the history and condition of the steadily-growing disparity between the North and the South, declared in effect that the South with its institutions could not permit Northern ascendancy, demanded from the North constitutional amendments "which would restore to the South in substance the power she possessed of protecting herself before the equilibrium between the sections was destroyed," added that on no other basis could the South safely remain in the Union, and said that, if this demand was refused, "we would be blind not to perceive that your real objects are power and aggrandizement, and infatuated not to act accordingly." To this candid avowal of the Southern programme (ten years later it became evident that Mr. Calhoun had stated then the slave power's ultimatum) the answer was the final surrender of 1850. The compromise measures of that year pledged the United States to the subdivision of Texas into new (slave) States, organized Utah and New Mexico without any prohibition