What Fleetlord Atvar
would have been called had the accursed Tosevites
behaved like sane
creatures and NOT industrialized
in the relative eyeblink of 1600 Home years (800 on Earth) in Harry Turtledove
Unfortunately, we Tosevites (what the Race calls us humans, of course!) had to be completely and mindbogglingly different from anything the Race had seen on either of the two worlds they'd conquered previously. Unlike the other known races, the Rabotevs and the Hallessi, who proceed at a steady (and to humanity, agonizingly slow) rate of technological evolution, humans just come up with things and start using them instead of testing them for a couple of centuries to make sure they're safe.
Of course, the Race didn't know this, so when they sent the probe to Tosev 3 and it sent back pictures of a sword-swinging barbarian the Race figured they had all the time in the world. Suprise: they didn't. They landed smack dab in the middle of World War II.