What are you referring to?
The only examples I know involve using animals to do the targeting. But all examples failed, as animals don't detect friend from foe. https://en.wikipedia.org/wiki/Military_animal#As_living_bomb...
I'd like to note that human being deciding when and where an attack should happen, never counts as "autonomous". Otherwise we have to count simple traps as "autonomous" weapons and the whole term becomes redundant. You could claim that any bullet shot while aiming through night vision goggles was "autonomous" because the shooter just set time and direction, but didn't really see who he was shooting at.
Second thought: you could claim that Japanese balloon firebombs and British balloon troops were using "autonomous" weapons. Then you would need to claim that changes in wind was the "AI". And strictly speaking that might be correct term. But then it's pretty easy to see why current hype about computerized "AI" has taken off in different way.