After his formal lament in Mormon 6, Mormon offered his final words of farewell. Remember that there was originally no chapter break or italicized section following his lament. The words in Mormon 6–7 were a single connected chapter in the 1830 edition of the Book of Mormon. Mormon’s primary audience here was his own people, and he pleaded with “the remnant of this people who are spared, if it so be that God may give unto them my words, that they may know of the things of their fathers.” He was giving all that he had left to the posterity of his people, and he was most likely trying to strengthen his only son Moroni as well in these last words of his final book within the Book of Mormon.
It is not known how many people were killed on the occasion of that final battle. Not all were killed, of course. Some would have fled. Their enemies continued to hunt them down and kill them, but only if they refused to “deny the Christ” (Moroni 1:2).
Mormon listed among the dead twenty-three of his generals, each with their ten thousand. That would seem to be a total of 230,000 men, but we do not know how the Nephites actually configured the units in their armies. In the Roman military, as a comparison, a unit of a hundred soldiers was called a century. A centurion was one of those hundred and would lead that unit. However, a century was still a century even if it had only fifty-two or seventy-five soldiers in it. We use a similar system for priesthood quorums. A quorum of deacons has 12, teachers 24, and priests 48, and an elder’s quorum has 96. There can be less, but not more in a quorum. The Nephite Ten Thousand may have been like these examples. Therefore, there may not have been a full company of 230,000 men who died at the final battle, to say nothing of the auxiliaries and civilians who would have been moving with this army. But the result, stated one way or the other, was still the complete elimination of all the soldiers that Mormon had led.
Book of Mormon Central, “How Could So Many People Have Died at the Battle of Cumorah? (Mormon 6:14),” KnoWhy 231 (November 15, 2016).
A. Brent Merrill, “Nephite Captains and Armies,” in Warfare in the Book of Mormon, ed. Stephen D. Ricks and William J. Hamblin(Salt Lake City: Deseret Book and FARMS, 1990), 285–286.