EDH on JS's reasoning behind Z story.
E. D. Howe, Mormonism Unvailed (Painesville: the author, 1834), 159
A large mound was one day discovered, upon which Gen. Smith ordered an excavation to be made into it; and about one foot from the top of the ground, the bones of a human skeleton were found, which were carefully laid out upon a board, when Smith made a speech, prophesying or declaring that they were the remains of a celebrated General among the Nephites, mentioning his name and the battle in which he was slain, some 1500 years ago. This was undoubtedly done to encourage the troops to deeds of daring, when they should meet the Missourians in battle array.