Imagine a future in which biological entities have developed self-repairing autonomous weapons of war that are each equipped with their own AI, that are faster, stronger, smarter, more durable, more reliable, more loyal, more obedient, cheaper and quicker to produce than the biological entities which produced them.
These autonomous weapons range in size from the microsocopic to the size of the largest ships, and where required, can be superficially indistinguishable to a member of the species that created them.
No single biological soldier, no matter how well trained, can face any of these autonomous weapons in combat and expect to win, and while victory for the biological entity is possible, it is unlikely and is usually more a matter of good luck than judgement or skill.
In such an environment, where a war may be fought between armies of opposing machines and where no biological combatant could expect to survive being present on the battlefield, what place do the biological entities have?
While the biological entities need not be human, this question doesn't preclude them from being human.
The biologicals are in charge. They dictate the military objectives and terms of engagement, and the AIs do the rest.
We can assume that the biologicals are divided into multiple polities, each with their own ethical stance, but the majority disapproving of things like wholesale slaughter of civilians, causing massive environmental damage, or polities that break these rules.
The weapons are made, maintained and operated by highly intelligent nanotechnology. They can be made anywhere that the raw materials are available, in as little as a day.
Nanotechnology is ubiquitous, but the quality of the weapons it can produce depends on the availability and quality of the software.
Even civilians can produce third-rate weapons at fairly short notice, but actively doing this would mark them as being legitimate military targets, akin to militia.
Technologically enhanced biologicals are still less capable than third-rate weapons - or are so far from their original form as to be able to be considered a different species.
Yes, the biologicals are the manufacturers and commanders of the AI weapons, however the question is "What place would biologicals have on the battlefield?", not "What is the role of biologicals in warfare?" - that is already obvious, as has been pointed out in comments.
In the event of an armed conflict involving AI weapons, would non-combatant biologicals in the battle zone be able to plod obliviously through the battlefield, confident that the AI weapons would avoid harming them, or would the biologicals be scrambling to build their own AI automaton bodyguards, or would some other situation occur? Could biologicals - enhanced or unenhanced - have an active military role, or would they all remain aloof from the conflict to avoid being targeted and killed?