The length and bitterness of that controversy excited the gravest apprehensions for the stability of the Union.  The dread of disunion led to mutual concessions, to the Missouri Compromise.  The slave-holding section got its immediate claim allowed, and the free States secured the erection of a line to the north of which slavery was forever prohibited.  And besides this, the admission of Maine was supposed to neutralize whatever political advantages, which would accrue to the South from the admission of Missouri as a slave State.  Both sections were content, and the slavery question was thought to be permanently settled.  With this final disposition of an ugly problem, the peace and permanence of the Union were viewed universally as fixed facts.  Still, considering the gravity of the case, a little precaution would not go amiss.  The slavery question had shaken men’s faith in the durability of the republic.  It was therefore adjudged a highly dangerous subject.  The political physicians with one accord prescribed on the ounce-of-prevention principle, quiet, SILENCE, and OBLIVION, to be administered in large and increasing doses to both sections.  Mum was the word, and mum the country solemnly and suddenly became from Maine to Georgia.  But, alas! beneath the ashes of this Missouri business, deep below the unnatural silence and quiet, inextinguishable fires were burning and working again to the surface of politics.  In such circumstances a fresh outbreak of old animosities must occur as soon as the subterranean heat should reach the point of highest combustibility in the federal system.  The tariff proved to be that point of highest combustibility.

Alexander Hamilton inaugurated the policy of giving governmental aid to infant manufactures.  The wisdom of diversifying the industries of the young nation was acquiesced in by the leading statesmen of both sections.  Beset as the republic then was by international forces hostile to democratic institutions, it was natural enough that the great men who presided over its early years should seek by Federal legislation to render it, as speedily and completely as possible, industrially self-dependent and self-supporting.  The war of 1812 enforced anew upon the attention of statesmen the importance of industrial independence.  The war debt, together with certain governmental enterprises and expenditures growing out of the war, was largely, if not wholly, responsible for the tariff of 1816.  This act dates the rise of our American system of protection.  It is curious to note that Southern men were the leaders of this new departure in the national fiscal policy.  Calhoun, Clay, and Lowndes were the guiding spirits of that period of industrial ferment and activity.  They little dreamt what economic evils were to fall in consequence upon the South.  That section was not slow to feel the unequal action of the protective principle.  The character of its labor incapacitated the South from dividing the benefits of the new revenue policy with