The study of history reduces to two tasks, Mencius Moldbug says — reading primary sources and assessing their credibility — and one good way to assess their credibility is to test their predictions against hindsight.
This test is especially useful when the prediction comes from someone on the losing side, powerless to make his predictions come true, like Confederate theologian R. L. Dabney, who made the following declarations in his Life and Campaigns of Lieutenant-General Thomas J. Jackson (1866):
History will some day place the position of these Confederate States, in this high argument, in the clearest light of her glory. The cause they undertook to defend was that of regulated constitutional liberty, and of fidelity to law and covenants, against the licentious violence of physical power. The assumptions they resisted were precisely those of that radical democracy, which deluged Europe with blood at the close of the eighteenth century, and which shook its thrones again in the convulsions of 1848; the agrarianism which, under the name of equality, would subject all the rights of individuals to the will of the many, and acknowledge no law nor ethics, save the lust of that mob which happens to be the larger.
This power, which the old States of Europe expended such rivers of treasure and blood to curb, at the beginning of the century, had transferred its immediate designs across the Atlantic, was consolidating itself anew in the Northern States of America, with a wealth, an organization, an audacity, an extent to which it never aspired in the lands of its birth, and was preparing to make the United States, after crushing all law there under its brute will, the fulcrum whence they should extend their lever to upheave every legitimate throne in the Old World.
Hither, by emigration, flowed the radicalism, discontent, crime, and poverty of Europe, until the people of the Northern States became, like the rabble of Imperial Rome, the colluvies gentium. The miseries and vices of their early homes had alike taught them to mistake license for liberty, and they were incapable of comprehending, much more of loving, the enlightened structure of English or Virginian freedom.
The first step in their vast designs was to overwhelm the Conservative States of the South. This done, they boasted that they would proceed first to engross the whole of the American continent, and then to emancipate Ireland, to turn Great Britain into a democracy, to enthrone Red Republicanism in France, and to give the crowns of Germany to the Pantheistic humanitarians of that race who deify self as the supreme end and selfish desire as the authoritative expression of the Divine Will.
By the way, you probably know Thomas Jackson by his nickname: Stonewall.