Apart from Ammonihah’s being destroyed, all in a single day, after the fifth day of the second month in the eleventh year (16:1, 10), the Nephites enjoyed a few years of peace until the Lamanites attacked again while chasing the converts of Ammon, whom Ammon had brought to the Land of Zarahemla. The Lamanites did not like that at all; they did not like losing all those people from their population. Thus, there was a bitter war in the fourteenth year of the reign of the judges. But then again, in the fifteenth and sixteenth years, peace returned. Notice also that the Zoramites in Antionum would also react bitterly when Alma and Amulek and other missionaries converted back and away many of the Zoramite working class.
Ammonihah, on the other hand, was destroyed as prophesied and in accordance with the Law of Moses, which sets forth the procedures to be followed against an apostate city. Many details in the account of the trial of Alma and Amulek in Ammonihah are based solidly on legal provisions in the Law of Moses (Figure 1). In particular, it appears highly likely that Alma had Deuteronomy 13:12–17 specifically in mind in his accusation against the wicked people in the city of Ammonihah. That biblical text provided that an apostate city should be destroyed and anathematized in a particular way, involving a thorough investigation that produced clear evidence that the inhabitants of the city had withdrawn to serve other gods and had become “children of Belial” (or of Satan; for that detail, see Alma 8:9), followed by execution by the sword, leaving the city as “an heap for ever” (Deuteronomy 13:16). Of course, Alma no longer commanded the armies of the Nephites, and thus he did not have the military power at his disposal to carry out the destruction of an apostate city by his own physical means, but in due time, God brought the scourge of war upon the city of Ammonihah at the hands of an invading Lamanite army that would “slay the people and destroy the city” utterly, killing “every living soul” (Alma 16:2, 9). And indeed, it remained a “heap” for at least seven years (perhaps a ritual fallow sabbatical period), from the beginning of the eleventh year to the end of the nineteenth year (see Alma 16:1; 49:1).
Figure 1 John W. Welch and Greg Welch, "The Law of Apostate Cities," in Charting the Book of Mormon, chart 126.
John W. Welch, The Legal Cases in the Book of Mormon (Provo, UT: BYU Press and Neal A. Maxwell Institute for Religious Scholarship, 2008), 238–271 discusses, among other things, the legal reasons why the women, children, and sacred books were burned, but not the men, who were banished (260–262); the legal significance of smiting on the cheek (263–266); the abusive imprisonment of Alma and Amulek (266–267); and the total infraction of all ten provisions of the code of judicial ethics in Exodus 23 (269–270), and thus articulating the justifications for the disastrous outcome in this case.
John W. Welch, “The Destruction of Ammonihah and the Law of Apostate Cities,” in Reexploring the Book of Mormon: A Decade of New Research, ed. John W. Welch (Salt Lake City and Provo, UT: Deseret Book and FARMS, 1992), 176–179.
John W. Welch, “Law and War in the Book of Mormon,” in Warfare in the Book of Mormon, ed. Stephen Ricks and William Hamblin (Salt Lake City and Provo, UT: Deseret Book and FARMS., 1990), 91–95.