By this time Mormon was around seventy-five years of age and he "began to be old." He therefore had all of the records and memorabilia of the Nephites placed in a cave of the hill Cumorah which Oliver Cowdery later described. This description is cited by Brigham Young in the Journal of Discourses 19:38. During this period Mormon had completed his summary of the Nephite history which comprises most of the Book of Mormon and had placed the record in the cave. However he turned over a few remaining plates to his son, Moroni, to finish the rest of the story.
Meanwhile, Mormon had arranged to organize the Nephites into tens, fifties, hundreds and thousands after the pattern set forth in Deuteronomy 1:15. Mormon assigned his best warriors over each group of ten thousand. Altogether he had 230,000 shock troops ready to meet the Lamanites. However this completely drained the military resources of the Nephites and left the women and children virtually unprotected in their tents. When the Nephites saw the tidal wave of Lamanites pouring down upon them, they were completely terrified. And thus the gigantic battle began. The Lamanites were taking no prisoners. All of the Nephites must die -- men, women, and children.