All units promoted simultaneously, why?

[AWildPlatypus]

Hey, I'm new to Vox Populi, this forum, and (relatively speaking) civ, so I apologize if I'm just missing something obvious.

During the industrial era, all of my units got a free promotion, but I don't know why. I didn't see anything on the wiki or from a brief search here. Anyone mind explaining what happened?

I've taken tradition, fealty, artistry, and freedom if that narrows it down at all.

On a side note, does having influential/dominant culture over another civ have any effect other than those related to capturing cities?

Thanks,
-A Platypus

 

[KlHannibal2]

Did you take a city the turn before that? There are city state quests for taking specific cities. The reward is xp for all units. This can lead to all or most units getting promotions. The xp is recieved one turn after taking the city.

The other way that comes to my mind is Sweden's ability.

 

[AWildPlatypus]

That must have been it and I missed the notification, thanks!

 

[Andrewspriggs]

There's also certain policies that will result in exp for all units. You said you had Freedom, so you might want to check if you had Self-Determination. That will give all units xp if you liberate a city.

On a side note, does having influential/dominant culture over another civ have any effect other than those related to capturing cities?

I think it also gives trade route bonuses and speed to espionage.