Juneteenth goes back 155 years. As Vox explains, “A portmanteau of “June” and “nineteenth,” Juneteenth marks the day in 1865 when a group of enslaved people in Galveston, Texas, finally learned that they were free from the institution of slavery. But, woefully, this was almost two and a half years after President Abraham Lincoln signed the Emancipation Proclamation.”

It seems though that Donald Trump wasn’t familiar with Juneteenth until earlier this month. Last night, in an interview with The Wall Street Journal, the president proclaimed that because he moved the date of his Tulsa rally, “I did something good: I made Juneteenth very famous. It’s actually an important event, an important time. But nobody had ever heard of it.”

It’s interesting to note that The New York Times reports that Brad Parscale, Trump’s manager campaign manager, also just learned about Juneteenth.

Mr. Parscale conceded he had not been aware of the holiday, multiple people familiar with the conversation said. But he responded that the campaign had held events on Jewish holidays, and last year held a “Merry Christmas” rally in Battle Creek, Mich., none of which were criticized as disrespectful to the people who celebrated those holidays. He said he thought it would not be a problem.

Perhaps the bigger problem is no one on the Trump campaign recognized the significance of June 19th or the history of Tulsa, Oklahoma, where, in 1921, a white mob burned to the ground an affluent black section of the city. Trump has a rally in Tulsa on Saturday.