Ammon, like his brother Aaron, is a missionary figure of the Book of Mormon. All four of the sons of King Mosiah—Ammon, Aaron, Omner, and Himni—were at first “numbered among the unbelievers” (Mosiah 27:8) and were “the very vilest of sinners” (Mosiah 28:4). But the Lord had an urgent, vital calling for these young men, and He sent an angel to intervene and bring about their spiritual transformation (see Mosiah 27:11–18). Afterwards, they went about preaching the gospel, confirming their testimony, and bringing about much good in their own land and later among the Lamanites with courage and enthusiasm.
Following their miraculous conversion, Ammon and his brethren desired more than anything else to declare the gospel of Jesus Christ to “every creature” (Mosiah 28:3). Thus they decided to embark on a missionary journey among the Lamanites that was to last fourteen years (approximately 90 b.c. to 77 b.c.; see Alma 17:4). Their preparation included much study, fasting, and prayer (see Alma 17:2–3). The Lord responded to their entreaties for a blessing by giving them comfort and assurance, promising He would make them instruments “unto the salvation of many souls” (Alma 17:11). For his part, Ammon was to journey to the land of Ishmael around 90 b.c., where he would win the respect of King Lamoni and his servants as a fearless defender of the royal flocks and herds—and then bring the gospel of Jesus Christ to the royal family and the entire nation (see Alma 17–18). Later, Ammon would provide a framework of strength and compassion to prepare the father of King Lamoni to respond to the missionary message of Aaron and come into the fold with much of his nation. Thus Ammon and his brethren would be instruments in establishing the gospel among the Lamanites.