Former Defense Secretary Jim Mattis, during a panel discussion, said he believed that the country’s education system needed to reemphasize certain principles, including teaching “the good, the bad, the ugly.” During his live-streamed talk with the Office of Strategic Services Society on Thursday, Mattis said he believed that education in the U.S. should not gloss over uncomfortable topics, such as the effects of slavery, which still reverberate in contemporary society. “As I look at the way American history is taught in our public schools, in many of our universities, I’m not sure how much affection I would be building in...