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In a single tweet, President Trump managed to both backpedal from and double down on earlier comments he made about Andrew Jackson being "really angry" about the Civil War.

On Monday night, Trump declared, "President Andrew Jackson, who died 16 years before the Civil War started, saw it coming and was angry. Would never have let it happen!" Many people are probably wondering where this tweet came from — why was Trump, seemingly out of the blue, bringing up the seventh president of the United States? And how does he know what Jackson felt? Did Frederick Douglass tell him?

It all started earlier in the day, when Trump spoke with Salena Zito on SiriusXM's POTUS channel. Much like a student who read a biography on a historical figure and could not keep what they learned to themselves, Trump continuously brought up Jackson. First, though, he asked Zito why more people "don't ask the question" of "why was there the Civil War?" It was the bloodiest war in U.S. history, but Trump is convinced that had Jackson been around "a little later, you wouldn't have had the Civil War." Jackson was a "swashbuckler," Trump said, "a very tough person" who "had a big heart." Jackson was also a slave owner who signed the Indian Removal Act.

Trump went on to say that Jackson was "really angry" when he "saw what was happening with regard to the Civil War. He said, 'There's no reason for this.'" Jackson did not say this because, as Trump noted in his tweet, he died in 1845, 16 years before the start of the war. For anyone interested in the life and times of Jackson — which again, took place well before the Civil War — there are several biographies to choose from.