Of course there were many Lamanites, as well as well as Amalekites and Amulonites, who did not join the Anti-Nephi-Lehies. All of these decided that the real enemy was not their fellow Lamanites but the main body of Nephites up around Zarahemla. So this state of mind called for a completely new military strategy.
Now our story has gone full cycle. We had wondered why a Lamanite army would cross the narrow strip of wilderness and sweep into the Sidon valley to attack the one city that was anti-Christian and in total sympathy with the abominable doctrines of Nehor. In one day this Lamanite army slaughtered the entire population of Ammonihah, the one city that would have gladly joined them as allies to fight the rest of the Nephites if they had been asked to do so.