Trump Civil War Remarks Show He Doesn't Know American History

U.S. President Donald Trump appears on stage at a rally in Harrisburg, Pennsylvania, on April 29, 2017. Carlo Allegri/Reuters

Hope you've had your coffee: President and noted Andrew Jackson fan Donald Trump kicked off the week's news cycle by asking why the bloodiest conflict in American history happened.

In an interview that aired Monday morning on SiriusXM, Trump told Washington Examiner reporter Salena Zito about his recent visit to the seventh president's grave in Nashville, Tennessee. While singing Jackson's praises, Trump said he was "a very tough person" with a "big heart" who was angry about the Civil War.

Related: A Brief Tour Through Donald Trump's Questionable Understanding of American History

"People don't realize, you know, the Civil War, if you think about it, why?" Trump said. "People don't ask that question, but why was there the Civil War? Why could that one not have been worked out?"

"Had Andrew Jackson been a little bit later, you wouldn’t have had the Civil War" @realDonaldTrump told @SalenaZito. Full intv at 2pE, Ch124

— SiriusXMPolitics (@SXMPolitics) May 1, 2017

Twitter users immediately jumped on the quote, pointing out that Jackson died in 1845 and the Civil War didn't begin until 1861. They also brought up that while many people have dissected the causes of the conflict, one of the major, widely agreed-upon reasons was slavery.

The Civil War Trust, a nonprofit that preserves the battlegrounds, quotes historian James McPherson on its website to explain the start of the war. He said:

"The Civil War started because of uncompromising differences between the free and slave states over the power of the national government to prohibit slavery in the territories that had not yet become states. When Abraham Lincoln won election in 1860 as the first Republican president on a platform pledging to keep slavery out of the territories, seven slave states in the deep South seceded and formed a new nation, the Confederate States of America. The incoming Lincoln administration and most of the Northern people refused to recognize the legitimacy of secession. They feared that it would discredit democracy and create a fatal precedent that would eventually fragment the no-longer United States into several small, squabbling countries."

The Civil War ultimately killed more than 620,000 Americans, according to the History Channel.

Monday's remarks weren't Trump's first U.S. history-related gaffe—or even his first 19th century-related one. In February, Trump spoke at a Black History Month event and praised abolitionist Frederick Douglass but used the present tense, according to CNN.

"Frederick Douglass is an example of somebody who's done an amazing job and is being recognized more and more, I notice," Trump said.

Douglass died in 1895.