It appears that the Lamanite king first covenanted with Zeniff peacefully (using "fair promises," Mosiah 10:18) and the treaty was apparently unalterable, but only during the Lamanite king's lifetime. Thus, when the Lamanite king died, his son apparently saw an opportunity to subject the Nephites to Lamanite rule and put Zeniff's people into bondage (see Mosiah 9:6). The Lamanites must have had a definite numbers advantage (see Mosiah 9:11) in order for the Lamanite king to think that he could bring Zeniff's people into bondage. Somehow he apparently didn't consider the resourcefulness of Zeniff's people to defend themselves (Mosiah 10:13-19). [Alan C. Miner, Personal Notes]