This was, and continues to be, in dispute.
Shortly after the battle, northern propaganda began the “massacre” theme.
After the war there were inquiries by federal authorities into the battle and claims that Forrest was a “war criminal.” Federal authorities certainly had the power to punish Forrest for any wrongdoing.
Either federal authorities couldn't find evidence that Forrest should be punished - or federal authorities decided to ignore the war crimes because . . . because why?
Because no southern jury would convict at that time???
“...or federal authorities decided to ignore the war crimes because . . . because why? “
Because evidence after a battle is very hard to collect, and because no one really KNOWS what happened. Even now.
One of my favorite generals wrote:
“The massacre at Fort Pillow occurred April 12, 1864, and has been the subject of congressional inquiry. No doubt Forrest’s men acted like a set of barbarians, shooting down the helpless negro garrison after the fort was in their possession; but I am told that Forrest personally disclaims any active participation in the assault, and that he stopped the firing as soon as he could. I also take it for granted that Forrest did not lead the assault in person, and consequently that he was to the rear, out of sight if not of hearing at the time, and I was told by hundreds of our men, who were at various times prisoners in Forrest’s possession, that he was usually very kind to them. He had a desperate set of fellows under him, and at that very time there is no doubt the feeling of the Southern people was fearfully savage on this very point of our making soldiers out of their late slaves, and Forrest may have shared the feeling.” - Major General William Tecumseh Sherman
Wiki has a good article here:
https://en.wikipedia.org/wiki/Battle_of_Fort_Pillow
I don’t think there is any doubt that in the heat of battle, many southerners behaved horrifically toward blacks who fought them. I haven’t seen any evidence their leaders pushed them to do so, or that it continued after tempers cooled.
Ding! They're just regurgitating Yankee propaganda put forth by a partisan newspaper in Cincinnati hundreds of miles away right before an election. In other words, there wasn't a shred of evidence. The Northern dominated Congress investigated and never filed any charges against Forrest because there was never any evidence against him.