WE DEMAND MILITARY PROTECTION! We don't care whose...

[The Mad Monk]

I often leave my early cities utterly undefended, depending on the AIs generally pleasant demeanors early on when you're diligent about open borders. So I had one city was smoking to to an unhappy citizen, which stopped smoking the next turn when an AI warrior visited. It started smoking again when he left, and on closer examination I discovered he removed the "no protection" penalty while he was there. I didn't expect that.

[rah]

Just make sure it's not an enemy warrior.

Yes, I was surprised when I experienced that for the first time. It's very rare since I don't leave cities undefended very often. It's usually when I have to move out a solo defender to pick off a barb or an enemy scout.

[Arslan230]

Its protection is very necessary and be careful .