The Book of Mormon on Self Defense

“And they were doing that which they felt was the duty which they owed their God; for the Lord had said unto them, and also unto their fathers, that: Inasmuch as ye are not guilty of the first offense, neither the second, ye shall not suffer yourselves to be slain by the hands of your enemies. And again, the Lord has said that: Ye shall defend your families even unto bloodshed. Therefore for this cause were the Nephites contending with the Lamanites, to defend themselves, and their families, and their lands, their country, and their rights, and their religion.”

Alma 43:46-47