There were certainly many battles that were incredibly bloody. Mormon has had to relate some of them, such as the one that inspired Alma’s great “O, that I were an angel” soliloquy. That battle “has brought to pass the destruction of many thousand lives; yea, it has brought to pass an awful scene of bloodshed” (Alma 28:10). Even with terrible loss of life, there was no description of the tactics involved or the battles themselves.
When Mormon describes tactics, it is typically to show how smaller numbers would defeat larger, or how the objective was won with lesser (or no) loss of life. Mormon clearly prefers incidents where he can report that an objective was taken without the terrible costs of many of the battles that had been fought, and certainly the battles that Mormon had seen in his lifetime, and will yet see, at Cumorah.