bonafide11
Worker
That is right, most do, but not all. For example, I had a Songhai Knight to Russian Cossak upgrade plan on a team game, but when I gifted my Songhai Knights to Russia and he upgraded them to Cossaks the city-bonus promotions were lost! I wanted to have city-killing-bonsus-vs-wounded cavalry! Boo!
I don't believe Songhai knights upgraded to Cavalry even maintain that promotion. I once was disappointed when I played them and found that my knights no longer that had that city-attack bonus.