Alma 28:9-12

9 And this is the account of the wars and contentions among the Nephites, and also the wars between the Nephites and the Lamanites; and the fifteenth year of the reign of the judges is ended.

10 And from the first year to the fifteenth has brought to pass the destruction of many thousand lives; yea, it has brought to pass an awful scene of bloodshed.

11 And the bodies of many thousands are laid low in the earth, while the bodies of many thousands are moldering in heaps upon the face of the earth; yea, and many thousands are mourning for the loss of their kindred, because they have reason to fear, according to the promises of the Lord, that they are consigned to a state of endless wo.

12 While many thousands of others truly mourn for the loss of their kindred, yet they rejoice and exult in the hope, and even know, according to the promises of the Lord, that they are raised to dwell at the right hand of God, in a state of never-ending happiness.

Did so many have to die? Why? Or why not?