A plaque that reads "The River of Blood" sits at the base of a flagpole between the 14th and 15th hole at the Trump National Golf Club in Sterling, Va., Wednesday, Dec. 2, 2015. The historical accuracy that "American soldiers, both of the North and South, died at this spot" has been called into question by historians. (AP Photo/Andrew Harnik)

(CNN) President Trump famously said the presidency was hard. Guess history is too. The President raised more than a few eyebrows over the weekend when he wondered, out loud, why the Civil War started.

Turns out the President's Civil War confusion dates back further than just a few days ago. A couple of years ago, Trump installed a monument to a Civil War battle that historians say never happened.

The monument, first reported by The New York Times in 2015, is at the Trump National Golf Club in Potomac Falls, Virginia. It's a stone pedestal with a flagpole between the 14th and 15th hole. On the pedestal is a plaque that says "The River of Blood."

"Many great American soldiers, both of the North and South, died at this spot. The casualties were so great that the water would turn red and thus became known as 'The River of Blood,' " reads the inscription.

Problem is, a Civil War battle didn't take place there.

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