In the late Roman Empire, soldiers on the frontiers began to imitate the style and fighting techniques of the Barbarians whom they fought, shedding their heavy metallic armor and uniforms and fighting in a more free-form, individualistic manner. Cultures in conflict often mutually converge, trying to take what seems effective from their adversaries and, at other times, mimicking their opponents simply out of degradation.

How morbidly fitting, then, that as we have brought about anarchy in Iraq and labeled it liberation, the false freedom of open borders has led to tribal killings of innocents at home, as blacks and Hispanics in Los Angeles terrorize one another in what sounds like a race war:

The Latino gang members were looking for a black person, any black person, to shoot, the police said, and they found one. Cheryl Green, perched near her scooter chatting with friends, was shot dead in a spray of bullets that left several other young people injured.

She was 14, an eighth grader who loved junk food and watching Court TV with her mother and had recently written a poem beginning: “I am black and beautiful. I wonder how I will be living in the future.”

“I never thought something like this could happen here in L.A.,” said her mother, Charlene Lovett, fighting tears.

Cheryl’s killing last month, which the police said followed a confrontation between the gang members and a black man, stands out in a wave of bias-related attacks and incidents in a city that promotes its diversity as much as frets over it.