A year ago Darren Wilson killed Michael Brown. What has followed has been the greatest national reckoning on racism since the beating of Rodney King.On Aug. 9, one year ago, Officer Darren Wilson shot and killed Michael Brown after a brief scuffle in the middle of a small street in Ferguson, Missouri. There wasn’t any video of the encounter, but many bystanders and local residents saw the aftermath. For four hours, Brown’s body sat in the summer sun, slumped and face down, blood pooling in the street where he was killed. Neighbors, shocked at the violence and the police’s disrespect...