Terrance Szink comments that in our third chapter of Third Nephi, Mormon inserted a most unusual document--a letter written by Giddianhi, the leader of the Gadianton robbers, to Lachoneus, the governor of the Nephites. This text is interesting because it is one of the few places in the Book of Mormon that provides a glimpse of the so-called "traditions of the fathers" that characterized the groups that opposed the Nephite nation. Another example of the presentation of the alternative tradition is the letter of Ammoron, a Lamanite king, to captain Moroni, written forty-seven years earlier and recorded in Alma 54. A comparison between the two is informative. In both letters there is a request for the surrender of the Nephites (Alma 54:18; 3 Nephi 3:6-7), although in the case of Giddianhi, it is more an invitation to Lachoneus to turn the people over to him and join with him in oppressing them. Both opponents claim that they have been wronged and that they have been unjustly deprived of their "rights of government." (Alma 54:17-18; 3 Nephi 3;10.) Both letters contain a rejection of God (Alma 54:21-22; 3 Nephi 3:2); and finally, both threaten destruction (Alma 54:20; 3 Nephi 3:3-4).
The differences in the letters demonstrate that in the case of the Gadianton robbers, the Nephites were confronted with an enemy much more sophisticated and dangerous than any previous. Giddianhi's letter mentions oaths and describes his organization as a "secret society" whose works are of "ancient date." (3 Nephi 3:9).
Another difference in the letters is the sophisticated tone of Giddianhi's message. He continually complimented Lachoneus, referring to him as "most noble," praising his "firmness" and his "noble spirit in the field of battle." He also claimed to be motivated by a feeling for the welfare of the Nephite leader.
A final difference is in the title of the two leaders. Ammoron was the "king" of the Lamanites, while Giddianhi was the "governor of the secret society of Gadianton."
The Gadianton band were a sophisticated and murderous group who were after both political and economic power. In his book, An Ancient American Setting for the Book of Mormon, John L. Soresnon sees control of trade as both a primary motive and a fundamental tactic of the Gadianton robbers. (see pp. 300-309) [Terrence L. Szink, "A Just and a True Record," in Studies in Scripture: Book of Mormon, Part 2, p. 128]