Fifty years ago Louis Armstrong was at the peak of his popularity. On May 25, 1956, Armstrong played to a crowd of more than 100,000 in Ghana, one of the largest crowds ever assembled to see a jazz performer up until that point. But Ambassador Satch was restless, and he was particularly unhappy with the vicious racism rampant at the same time in the American South.

“They treat me better all over the world than they do in m...