The Book of Mormon records frequent warfare, and it is sometimes difficult to understand why these wars started. Comparing descriptions of events leading up to war in the Book of Mormon with other historical war accounts suggests that one possible cause of contention involved people trying to take advantage of transitions that occurred at the death of a powerful figure. For example, continual crises and wars occurred just about every time a powerful Roman general or leader was killed throughout the decades of Roman civil wars. Naturally, wars happened at transition points like this in the Book of Mormon as well.
The first chapter of Alma explains what happened shortly after the death of the great leader and king, Mosiah, and very soon after the implementation of a radical new form of government where Nephite kingship was replaced by a form of democracy with judges chosen by the people. During Alma’s first year as chief judge, a man named Nehor rose against Alma and the church. Nehor’s opposition did not immediately lead to war, but by the fifth year of the reign of judges, the movement Nehor started led to a full-fledged war when the Lamanites supported Amlici in his attack against the Nephites.
Wars happened at other transition points in the Book of Mormon as seen in later war narratives. For example, many of the Lamanites converted to Christianity through the preaching of Ammon and his companions. "[T]he Amalekites and the Amulonites and the Lamanites who … had not been converted and had not taken upon them the name of Anti-Nephi-Lehi, were stirred up by the Amalekites and by the Amulonites to anger against their brethren" (Alma 24:1). Those joining in the rebellion did not like who was appointed king. Significantly, the timing of this war happened around a time of transition from one king to the next. Alma 24:3–4 explains, "Now the king conferred the kingdom upon his son, and he called his name Anti-Nephi-Lehi. And the king died in that selfsame year that the Lamanites began to make preparations for war against the people of God." The fact that an inexperienced king sat on the Lamanite throne may well have been a contributing factor in the commencement of this war.
Again, in Helaman 1:2, another succession crisis ensued when Pahoran died and Pahoran’s sons contended for the judgeship. When Pahoran’s son took office, Kishkumen assassinated the chief judge and the Lamanites took advantage of the chaos to invade Nephite territory.
One further example of war breaking out during a succession of power is described in Alma 45:19–20 and 46:1–3. This occurred when Helaman took over after the death or disappearance of his father, Alma. History was repeated when Amalickiah took advantage of the uncertainty caused by Alma’s death to rise up against the less experienced Helaman.
Book of Mormon Central, "What Was One of the Main Causes of Warfare in the Book of Mormon?" KnoWhy 523 (July 5, 2019).