John L. Sorenson explains that:
The prevailing expert view has long been that Mesoamerica was largely free from military conflict.
In recent years that view has begun to change to a picture more like that conveyed in the scripture— that warfare was a frequent or even dominant concern with profound consequences for ancient society.– Fortifications in the Book of Mormon and in Mesoamerica – Sorenson, John L.
As well as the Book of Mormon correctly including so many wars, the descriptions of war are surprisingly accurate and not what we would reasonably expect Joseph Smith to be able to create on his own. One example is that of watchtowers, fortifications and strongholds.
Fortifications are mentioned 24 times in the Book of Mormon such as in Alma 48:8:
Yea, he had been strengthening the armies of the Nephites, and erecting small forts, or places of resort; throwing up banks of earth round about to enclose his armies, and also building walls of stone to encircle them about, round about their cities and the borders of their lands; yea, all round about the land.
These descriptions are consistent with what we now know about pre-Columbian America, but where would Joseph Smith have learnt this? How was he able to correctly describe watchtowers, fortifications and strongholds?