The recently televised debut of "The Young Indiana Jones Chronicles" was quite entertaining but flawed historically. The cavalry troops serving under Gen. John J. Pershing were black, not white. My stepfather, Victor Humphries, soldiered in the famous punitive incursion into Mexico and was wounded in the campaign. Pershing was not called Black Jack because of the hue of his hair or the shade of his horse but for the color of his cavalrymen.
Pershing was nicknamed Black Jack when he fought with the black 10th Cavalry Regiment in Cuba in the Spanish-American War.