Lincoln’s Tariff War
Though Northern agitation toward African slavery, especially fomenting slave insurrection in the American South, pushed the Southern States to political secession, economic questions that had been weakening the fraternal Union since 1788 had become a paramount concern of Northern business interests in early 1861. Those interests would not accept an independent South with a lower tariff structure which would leave Northern ports idle, and helped influence Lincoln to wage his destructive war.
Bernhard Thuersam, Chairman
North Carolina War Between the States Sesquicentennial Commission
"The Official Website of the North Carolina WBTS Sesquicentennial"
Lincoln’s Tariff War:
“Dr. Tyler shows how Lincoln refused to see the Confederate Peace Commissioners, and goes into the matter of the reinforcement of Fort Sumter, in which Lincoln persisted, although warned by his Cabinet that it surely meant civil war.  This brings to mind the recent declaration of a Chicago university professor, who could claim a Southern birthright, that [Woodrow] Wilson’s course in thrusting the United States in to the Great War will be as fully justified by history as was Abraham Lincoln for “entering upon” the devastating war of 1861.
Beginning the war, as Lincoln unquestionably knew the reinforcement, or attempt thereat, of Fort Sumter meant, was due, says Dr. Tyler, to the determining influence of the tariff.  “There was a Confederate tariff of 10% to 20 % and a Federal tariff of from 50% to 80%, and fears of the successful operation of the former excited fears in the bosoms of Lincoln and his cabinet and the Republicans generally.
Considering the enormous interests that centered around the tariff and the fact that in 1833 the tariff question had actually pushed the country to the verge of war, this explanation is not at all unreasonable.  As early as March 16, Stanton, not yet aligned with the Republicans, had noted the apprehensions of that party, and the New York Times of March 30 had observed: “With us it is no longer an abstract question, one of constitutional construction or reserved or delegated power of the States to the Federal government, but of material existence and moral position both at home and abroad.”
The apprehension had grown, weakened the opposition in the cabinet and induced Lincoln to take tentative action in ordering the preparation of a fleet for Fort Sumter. Final action was the result of the concourse at Washington of seven, or as others have it, nine governors of high tariff States, who waited upon Lincoln and offered him troops and supplies.
In the interview…on April 4….with the delegates from the Virginia Convention…and the deputations from each of the five Christian associations of Baltimore,, who spoke for peace, on April 22, Lincoln asked: “And what is to become of my revenue if I let the government at Montgomery with their ten per cent tariff, go on?”
(John Tyler and Abraham Lincoln, Dr. Lyon G. Tyler; book review by A. H. Jennings, Confederate Veteran,  June 1929, pp. 212-213)