Oh OK. However the Loyalty system is AFAIK a sophisticated part of the new Happiness system. Happiness in Civ V is a mess, every game I would have to obsess about keeping the masses titillated. It's not a bad concept though, it was just badly done. In VI you see the changes, per city, and now Loyalty which is a measure of how great you are relative to your neighbors. At least that's how Ed Beach described it in one of the Dev Plays (the 'how great' idea). Encampments give lots of buffs - promotions, strategic resource loosening, I'm not sure adding a Loyalty buff works (in fact Citizens might not like having soldiers everywhere!)
Interestingly it was my Garrisoned city last night that flipped. They didn't have enough amenities and housing which was the main problem I couldn't address in time, which shows the Happiness aspect.