... Trump, who has previously paraded his historical ignorance, most famously in his remarks on the Civil War era abolitionist Frederick Douglass, seems to be resuscitating the “needless war” school of Civil War causation that most historians thought they had put to bed in the 1940s.

This school of revisionist historians not only downplayed the sectional conflict over slavery, but also argued that a blundering generation of politicians had led the country down the path of war. ...

Lincoln understood the bloody meaning of the war much better than current Republicans. In his second inaugural address, he said that if God willed that the war “continue, until all the wealth piled by the bondman’s two hundred and fifty years of unrequited toil shall be sunk, and until every drop of blood drawn with the lash shall be paid by another drawn by the sword, as was said three thousand years ago, so still it must be said the ‘the judgments of the Lord, are true and righteous altogether.’ ”

Douglass, Trump might care to know, called this speech “a sacred effort.”

If Trump was calling for compromise over the issue of slavery to avoid war, then he might also learn from the actual tawdry history of compromise in 19th century America. The Compromise of 1850 enacted the draconian Fugitive Slave Act, which demanded that all American citizens act as slave patrollers. It and other such attempted deals came at the direct expense of black lives.

Even a moderate anti-slavery politician like Lincoln, who was willing to allow the existence of slavery in the South to prevent disunion and war, drew the line when it came to the expansion of slavery into Western territories.

It could very well be, of course, that Trump, like some Republicans, does not think that the abolition of racial slavery was worth the cost of war. If that’s what he believes, he should say so.