Alma 17
Mosiah was desirous to confer the kingdom on his sons. I’ll bet that their decision to leave on a mission directly led him to the idea of altering the system of government – perhaps it was even part of his prayer regarding whether they should be allowed to go.
If Ammon knew of the promise of the Lord that he (and his fellow missionaries) would be protected he would have been all the more confident that the sheep could be gathered and that he could contend with the men who were scattering them.