Do some research. This was a promise made by a Civil War General to a specific bunch of people which was later rescinded by the president. There was no general law or promise that such would be provided to every freed slave. It happened for a brief period, in a relatively small location (Georgia) And it happened 150 years ago.

Aside from whether somebody was put into harm's way because his great-great-great grandfather missed out on the free mules, I just wanted to clarify that historical point. It's one of those historical revisions that seem to grow with the retelling.