I remember very little about this story, but here goes.
It involved a small team of anthropologist types, who were using a humanoid machine to interact with local primates in a remote planet. They would teach them nightly, I think, about things like fire.
But just as they were making progress, they were called away to serve in some sort of all-consuming war for their galactic empire (I distinctly remember a line about this... i.e., something about how everybody was swept up in that conflict.) And the project languished.
I stumbled upon the story maybe 8 years ago. I'd have said it was a few decades old at that point.
The thing itself was an online PDF.