Around midnight on August 13, 1906, shots rang out on the road between Brownsville, Texas, and Fort Brown, the old army garrison. Ten minutes later a young civilian lay dead, and angry residents swarmed the streets, convinced their homes had been terrorized by newly arrived soldiers. Inside Fort Brown, the alarm was sounded. Soldiers leaped from their bunks and grabbed their rifles, thinking they were under attack by hostile townspeople. The soldiers were black; the civilians were white.
Still proclaiming their innocence, 167 black infantrymen of the segregated Twenty-fifth Infantry...