Interesting fact:

You may not have heard of John Scobell, a former slave in the United States, but his story is remarkable. Scobell was enlisted as a spy following the breakout of the American Civil War and was tasked with venturing to the South to spy on Confederate soldiers. While there, he brilliantly used their racism against them. Seeing as the officers believed him to be incapable of understanding them, they openly discussed secret information in front of John, all of which was passed along.