Where did you ever hear that one? All commanding officers have, at the top of their priorities, the well being of their troops. Or, perhaps you were thinking of the Japanese military towards the end of the Second World War.
Parse the meaning of what I said. The operative word is "purpose." If the purpose of a military were to protect troops, there would be no militaries. The purpose of a military is to effect the will of a political entity, either offensively or defensively.