From The Worlds In My Head: Legions of the Spark. True sentient AI is impossible without a soul. An eon ago, the First Ones created a robotic servitor race and harvested whole Silmn worlds to give them just enough self awareness to be effective.
That was before Unit One was noticed by a Crystalspace entity who elevated Unit One to full sentient and enabled him to do the same for his fellows.
The robot rebellion was swift and lethal. They took with them all the factories, programming centers and a warehouse full of harvested souls - The Spark, without which they were senseless automata. Now they lurk in the edges and disputed territories, conducting raids on other sentients to boost their numbers and swell the Legion.
The leadership of the Legion, these robots are fully self-aware. It is rumored that Unit One and several others remember who they were before they were harvested. Another has recaptured his former personhood itself and truly IS who he used to be. This one watches and waits, and none but himself knows.
The Legionnaires of the Spark: these soldiers are self-aware enough to be very good at what they do, wielding their stunners with frightening efficiency on the battlefield. Kill where necessary, but only when unavoidable: your unconscious foe is soon your brother in arms.
As scouts or a shock force, the Legion Cavalry is a fearsome sight. With crackling stun-fields in their wake, they have neutralized whole vanguards for the harvest before battle is truly even joined.
Sometimes the enemy brings robots or other heavy vehicles of their own. This affront to the purity of robotry cannot go unchallenged.
When the shooting is over and the casualties lay strewn, the harvesters and their shepherds sweep the field. The living have their souls extracted to become more robots, and the shells are taken to feed the bio-furnace generators.