What color was General William Tehcumseh horse named Duke?

There is no historical record of General William Tecumseh Sherman owning a horse named Duke, nor is there any information about the color of such a horse.

It's important to note that while Sherman was a prominent figure in the Civil War, there is no evidence he had a horse named Duke, or any horse that was particularly famous or documented.

It's possible this is a fictional detail from a book or movie, or a misremembered anecdote.