Slitherine

In prior playthroughs, it seemed that a siege was initiated when your border completely surrounds a city. However, I'm now playing as the German tribes and surrounded the Dacian capital, even with four units around it, and nothing happens. Similar later with the city to the north of it. I couldn't find anything at all in the in-game rules (although I remember reading about it - perhaps in the manual?) so I ask here. I'm obviously missing a game mechanic - what actually starts a siege?

Also, does supporting population do anything at all without any cities? My population has stayed at zero (the Dacien settler switched sides and immediately used all my food too ) with it cranked up to 100% so I know it doesn't add population but, does it use gold under this circumstance?

Hello lordhoff,
regarding the siege there is an anwser in manual (page no. 204) - City siege. To quote the part you are probably missing:

If one of your cities is under siege, you can either try to break through
the enemy lines or, if the city lies on a coast, you can send a naval unit to
provide the necessary supply link for the city (the ship needs to enter a tile
adjacent to the city

If this is not the case, it means that the city has border with another player and the owner of that city is in peace with that neighbour. If I am wrong, please send ne screenshot or save file to my email address.

Regarding your second question - if you have no cities, setting any value of birth rate support has absolutely on impact (no resource consumption, etc).

I never got back to this but the issue was that this was my first game using the noob setting which has supply turned off by default.

Thank you for clearing this up!