That argument is not only oversimplified it is flawed.

Slavery was an issue but not the main cause of the Civil War. Money was the cause of the war between the North verses the South. The slave fleets never operated out of southern ports. They operated out of Boston, Mass, Providence, Rhode Island, later joined by New York City. Fact is Massachusetts had slavery 78 YEARS LONGER THAN MISSISSIPPI. The Lincoln administration did nothing to stop these Northern slave trade routes because they continued until 1885. The real cause of the war was Northern corporations and Washington D C. In 1859 the value of all Northern corporate exports was $70,000,000. The same year the value of Southern exports was $161,000,000. southern states were paying 82% of the U. S. taxes year over year yet the South was only 29% of the U S population at that time. To further break the backs of the South, President Lincoln approved the increase tariff from 24% to 47% on the South and the rate stayed in effect until 1913, except for the Civil war years. The money collected by the tariffs went to Northern corporations, Wall Street and, Washington D C.
 

Lyndon B. Johnson, U. S. Senator from Texas along with the Democratic party advanced the modern incarnation of identity politics in 1960. He blamed the cause of the Civil War only due to one reason, slavery. Lyndon Johnson is the inventor of racism in America. He became the President after President John F. Kennedy was shot to death in 1963.

Fact #1. In 1956, 75% of African-Americans voted for Republicans. After eight years of the democratic party engaging in brainwashing of the black community, they now voted 90% for democratic candidates in the 1964 elections.
 

Fact #2 - This brainwashing by the Democratic party turned the tide of the black voters and the story of the Democrats not responsible for slavery. Lyndon Johnson was able to shift to racism on behalf of the Republicans wanting slavery as a way of life, to continue in America, which is totally not the case. It was a Republican congress that abolished slavery in America. Johnson made the Civil war all about slavery and race he, along with the Democratic party, never exposed the Northern hypocrisy or the Northern greed of companies backed by Wall Street, which caused the war in the first place. The fix was in, the democrats are responsible for the lie, and they keep telling the lie over and over again. Why would the Democratic party stop the Civil War cover
up? Because this cover up has been working well for them for the past 66 years.

Mitchell Morrison
Cover-up Historian 
Volume 1.