there are no innocents
the concept was developed to allow lawyers to control the military and the war process
That's simply untrue.
Every ethic or law pertaining to war, going back to Aristotle and Thomas Aquinas, and right up to and including the tribunals after WWII and the laws encoded in the UCMJ, features the concept of "discrimination" --- that acts of war must attempt to discriminate between armed and disarmed persons, between combatants and non-combatants.
Not that anyone could do this perfectly, since under the ambiguities and stresses of war, this can be devilishly difficult --- but that has to be the active intent. And it has been the active intent of every good soldier in American history.
It has been important to recognize that there are innocents -- in the sense relevant to matters of war and combat --- ever since God said "I hate the shedding of innocent blood." That takes you way back before lawyers, brother.
If you have no fear of God --- then go ahead and kill indiscriminately. But the man who has no fear of God and who kills indiscriminately, is not fit to be a soldier. Be aware of Whose law it is you're rejecting, and Whose power you are forfeiting.