On June 13, 1863, Nathan Bedford Forrest got into an argument with one of his artillery officers - Andrew Wills Gould - about the latter's upcoming transfer. This confrontation escalated into a violent exchange, with Gould shooting Forrest and Forrest stabbing Gould. Gould's wound proved fatal, and it was initially thought that Forrest's injury would prove mortal as well, but he recovered.
What if it had been a true mutual kill, with Forrest succumbing to his wound?