This is an oral story in regards to black troops in Kansas in the 1870s, principally in Hays City. I have never seen any documentation where six black troopers were killed in a civil disturbance in the West. Also, the Ninth Cavalry, to best of my knowledge were stationed at the time of this story (1870s) in Texas. The storyteller may have been referring to the Tenth Cavalry. I would take this story with a grain of salt.