Slitherine

550BCE campaign, I am Athens and asked to get Lydia as a client state for a mission with extra legacy. It suggests that at least the capital has to be held. So I take the capital with my army. I am now at a loss of how to turn them into a client state? Liberate doesn't work, they become a client state of another name, but don't fulfil the mission.

That's the correct process but in the current version you can get Lydia or another nation. In the next patch Lydia will have priority...

Ace, ta

Defeat a major power and occupy most of their regions. If you offer peace. with a client state requirement and more, they will accept because they receive their unconquered regions back.