One August day almost seventy years ago, a Texas governor ignored the law and sided with a white mob. It was school registration day in the then-tiny town of Mansfield, southeast of Fort Worth. Earlier that week, a federal judge had ordered Mansfield High School to integrate, so that Black students could attend the local high school rather than continuing to travel twenty miles, via Trailways bus, to the Black high school in Fort Worth. The decision had infuriated many white residents. In the days before the judge issued his decree, two crosses had been burned in the Black part of town.Now, a crowd of several hundred amassed outside the high school. Effigies of Black men in nooses had been hung from the flagpole outside…