There was a question of the number of people Forrest personally killed, one way or another, and it can actually be tallied up the hard way by going through the records and reports, and eye witness accounts. For example, at Sacramento there were two killed and three sabered...no indication of who sabered them but there were six Union men who surrounded Forrest after he'd been thrown off his horse and dislocated his right shoulder. Two were killed by his men defending him and the other three had to have been done in by Forrest, busted wing or no! As it happened, Forrest was reckoned to be a master swordsman, a skill taken up by many planters, so he was perfectly capable of very quickly dispatching all comers via his double edged saber. Earlier, while leading the charge into the battle, Forrest ran his sword through the Union commander. That's 4 right there...and just about every battle where Forrest found himself engaged in personal combat, 4 to 6 guys were dead when it was over.
The secret was probably Forrest's astounding temper and the equally astounding transformation it made in him physically. The Hulk! Until he slept it off, he was just as dangerous after the battle - enough so his staff gave him as wide a berth as possible. Sometimes the word would go out: "Get Old Missus." That was the men's name for Mary Ann - she could calm the general down when no one else dared get near him!