A few years ago I started making an overview of all the wars in the Book of Mormon: When they occurred, who was involved, how it was initiated, etc. It was a bit difficult since there are so few details sometimes, like Enos just saying that "I saw between the Nephites and Lamanites in the course of my days." (Enos 1:24). I don't know exactly what I expected to get out of it, I just thought it could be interesting. Although I didn't really finish it, I made at least one observation that I thought was interesting: Every single war during the reign of the judges until the coming of Christ (Alma, Helaman, 3 Nephi up to chapter 11) is initiated by Nephite dissenters and never the Lamanites. And these are a lot of wars too. Here is an overview:
87 B.C. - Amlici wants to be king, the Nephites vote against him, he gets mad and mixes goes to the Lamanites along with his followers. They go to war against the Nephites. See Alma 2.
81 B.C. - The Sons of Mosiah had been preaching among the Lamanites and had much success. Many Lamanites converted but none of the Nephite dissenters among them (Amalicites and Amulonites) except for one. Instead they stirred up the others that had not converted to anger against the converts and later the Nephites and went to war against them. See Alma 16 and 28.
74 B.C. - In the aftermath of the Zoramite mission, those who believe are cast out and those who don't believe are mad at the Nephites for giving them refuge and land. They mix with the Lamanites and go to war. See Alma 43-44.
73-57 B.C. - Amalickiah is another one who seeks to become king. When it doesn't work he goes to the Lamanites and eventually even becomes their king. But he is not happy with that and goes to war against the Nephites. There is at least one period of peace in-between, but all the wars going on in this period are initiated by Amalickiah and perpetuated by his brother, Ammaron, when he dies. This is a long one and is covered in Alma 46-62.
52 B.C. - We get little information about this one but enough to know that it is caused by Nephite dissenters stirring up the Lamanites to anger. See Alma 63:14-15
50 B.C. - We don't know much about the background for this war, just that the Lamanites came. But we learn that their armies were led by someone called Coriantumr who was a Nephite dissenter and that the king stirred them up. The Lamanite king at the time was Ammaron's son and Amalickiah's nephew, i.e. a Nephite by birth. See Helaman 1:14-34
38-30 B.C. - History repeats itself. Nephite dissenters go to the Lamanites, and manage after some persuation to stir them up to anger against the Nephites and go to war. They capture a lot of Nephite land, but give it back after a lot of them convert through miraculous events. See Helaman 4-5.
15-16 A.D. - This is the longest period without wars between Nephites and Lamanites in the reign of judges. But there has been much unrest at times and the Gadianton robbers have been established and have taken over much of the government and caused murders and plundering. It is hard to pinpoint a war in this period until 15-16 A.D. where more of a battle is described between the Nephites and the Gadianton robbers. Not surprisingly, the Gadianton robbers originate from Nephites. See 3 Nephi 2:17-18.
19-22 A.D. - Another battle with the Gadianton robbers. At this point, the terms "Nephite" and "Lamanite" seem to have little to do with who their forefathers were. "And it came to pass that those Lamanites who had united with the Nephites were numbered among the Nephites" (3 Nephi 2:14). Considering all the Nephite dissenters who have joined the Lamanites before this, a genetic test would probably fail to determine who is who. See 3 Nephi 4.
Depending on how we count, we have about 9 distinct wars in this period of judges. Every single one is initiated by people who were Nephites by birth. In fact, at least in two of these accounts, there were Lamanites who refused to go to war and had to be persuaded by Nephite dissenters. See Alma 47:2 and Helaman 4:3.
I guess Mormon was right:
And thus we can plainly discern, that after a people have been once by the of God, and have had great of things pertaining to righteousness, and then have away into sin and transgression, they become more , and thus their state becomes than though they had never known these things. (Alma 24:30)