If I remember correctly the infantry unit was surrounded and killed as well.I visited the site several years ago, it was a perfect place to set up the fights that we now call the "Fetterman Massacre". The command left the fort with a mixed unit of cavalry and infantry to pursue some Indians that had appeared to the sentries. The cavalry pulled away from the infantry and got sucked into an ambush that killed all of them. I don't recall how the infantry faired after that. It's been many years since I was there.