The dominant narrative about the causes of the Civil War is the work of historians obsessed with social activism instead of history.
They point to the 13th, 14th, and 15th postbellum amendments as proof that the North was ultimately fighting to provide slaves with honorable freedom, but deny that the increase in tariffs on dutiable items from 19 percent before the war to an average of 45 percent for 50 years thereafter reflected a Northern war aim.
They hold Southern secession responsible for the war, but fail to teach that the Northeastern states threatened to secede five times between 1789 and 1850. They also decline to note that Southern secession need not have led to war. Southerners had no purpose to overthrow the Washington government; they merely wanted a government of their own. Northerners could have evacuated Fort Sumter and let the first seven cotton-states depart in peace, thereby avoiding the war.
Modern historians normally focus on the reasons the cotton-states seceded, instead of examining the economic reasons Northerners chose to militarily coerce them back into the Union, thereby inaugurating civil war.
The Republican party could have stopped the spread of slavery peacefully by endorsing popular sovereignty during the presidential election of 1860. After Kansas used it to reject slavery in an local-option vote in 1858, nearly every politico realized that the doctrine would quarantine slavery in the South. If popular sovereignty could not make a slave state out of Kansas, it could not do it to any of the remaining federal territories of 1860. Republicans rejected the doctrine simply to survive as an independent party because Lincoln’s main two opposing presidential candidates supported it. Beyond what poplar sovereignty would have gained, the Republican blanket-ban on slaves in the territories added nothing except to inflame the sectional passions that led to civil war.