Alma 48
Amalakiah did not intend to fail which is why he wanted all the Lamanites, and not just half, to go to war against the Nephites. He knew that they did not want to be forced to go to war, but once he was acknowledged as king they could not stop him from his campaign of propaganda. By the time he took them to war they did not feel coerced because their hatred had grown and they had not identified that he had caused that.
Moroni did not teach the Nephites to hate the Lamanites in order to fight them more effectively. Instead he taught them to love their liberty and to recognize it as a gift from God.