Mormon not being killed with his ten thousand troops (v. 10) must have been an act of God. Abinadi was not destroyed until his message and his mission was completed (see Mosiah 13:3). The Prophet Joseph Smith was not martyred until his mission was fulfilled (see TPJS, 258, 274, 328, 361). Mormon was chosen by the Lord to both abridge the records and bear testimony of the Nephite destruction. His work was not quite done in this final battle described above. Both Mormon and Moroni were among the twenty-four survivors (Mormon 6:11). Between these two great men, fifty pages of our present-day Book of Mormon were given to us. These fifty pages are an important and necessary addition.
We do not know how long this final battle lasted. It appears to have been very long. There were twenty-three groups of ten thousand men who were killed in this terrible slaughter (vv. 10–15). Although a few others deserted or escaped, basically only one man out of each ten thousand men survived. As had been foretold, The Nephite nation had “become extinct” (see Alma 45:10–14; Helaman 13:9–10).