Unit promotion

[Abydos2024]

Every once in a while I will go to create an army in one of my cities. I select the unit and press x to create army, however the option to create army is replaced with upgrade unit. I have the option of picking a new promotion for one of my single veteran NEWLY created units, never been in combat units. I have no idea why or how this happens, I can't figure out if it's tech or a great person that makes the city do this. Please help, this has to have happen to someone else. Ex: select build tank>rush tank>next turn press x upgrade unit>infiltration or blitz. Only units built in that city get this option.

 

[Chinese American]

Some things can grant free promotions and veteran status. Such as buildings (barracks), civ-specific abilties (russians, i think), world wonders, etc. I don't remember if settling a great general also does this, but that could be it.

 

[ArchGhost]

Barracks+Settled Great Leader gives units created in that city 6 exp, enough to take a promotion immediately without combat. You have a Great Leader settled in that city along with a Barracks.

 

[Abydos2024]

Thank you that answers my question.