Egypt's Iron Clads Act Like "Slingers"

I am playing as China and am at war with Egypt. We've been having a naval battle, and one of his Iron Clads moves out of the way when I try to fire on it with my iron clads. I click to attack, and the thing scoots a tile away. I move up to it and fire again, and it scoots a tile away.

Just one of them is doing it. Is there some kind of special promotion for naval units to evade being fired upon?

All caravels now get the same retreat promotion as slingers. The ironclad could have been promoted from a caravel (though the fact that AI rarely upgrades leads me to try and think of another explanation and I cannot).

^^Really? I had no idea that caravels had a retreat promotion.

I guess I'd better see what else I'm missing.

Thanks