Undefended cities

[Osvaldo Manso]

I'm sure that most experienced players have noticed this but maybe this is fresh news for someone out there:

I don't know why, but the game doesn't regard capturing a city as aggression. For diplomatic purposes, it has far more consequences destroying an enemy unit than capturing an unguarded city.

So, when you find an undefended city (without any unit inside the city) from another civilization, always capture it. Even if you are at peace with that civilization and you want to remain at peace with them, don't hesitate. You will earn some money, maybe a technology and, most important, it will slow down the other civilization's development. In the next encounter, the other civilization will talk to you as if you were not at war but as if you are neutral. Most of the times they will offer a peace treaty.

Normally, undefended cities are newborn cities with size 1. Capturing the city means destroying it. If the city has a size bigger than 1 and you don't want to keep the city for your empire, there are several solutions (starving the city until destroying it, letting another civilization or barbarians capture it, etc).

On the contrary, if you made peace with a particular civilization and you leave a city undefended, that civilization's units will not enter your city even if they pass nearby.

 

[Urtica dioica]

Surely it has something to do with the fact that capturing a city requires no attack points; a settler can do it. Another oddity is that you can attack with a ship, but not capture.

Careful though. One time I was searching for huts with my first settler and found a size 2 capital of another civ. They hadn't had time to build a defender, so I walked in. Big mistake. I got no palace, and when I finally placed my settler, I got no palace there either.

 

[Tenochtitlan]

I've had my invasion of an unguarded enemy city break our treaty, and I've had peaceful opponents occupy my unguarded city and left our treaty intact (which is especially annoying under Republic or Democratic governance

 

[Tenochtitlan]

Surely it has something to do with the fact that capturing a city requires no attack points; a settler can do it. Another oddity is that you can attack with a ship, but not capture.

Careful though. One time I was searching for huts with my first settler and found a size 2 capital of another civ. They hadn't had time to build a defender, so I walked in. Big mistake. I got no palace, and when I finally placed my settler, I got no palace there either.

Aha, maybe if you attack with a settler, it doesn't break treaty, and doesn't even ask you if you want to break treaty. It makes sense.

 

[Osvaldo Manso]

Let me clarify things a little bit:

The situation I've described requires previous contact and the establishment of a peace treaty with the other civilization. Later, when I find an unguarded city and try to capture it, a message appears on the screen asking if I'm sure about breaking the peace treaty. If I select "Yes", I capture the city. The next time I make contact with that civilization (if they possess any remaining cities) they don't treat me as if we were at war. Instead, they act as if we have never met before.

So, I'm talking about breaking peace treaties without the danger of triggering war.

 

[Osvaldo Manso]

I've had my invasion of an unguarded enemy city break our treaty, and I've had peaceful opponents occupy my unguarded city and left our treaty intact (which is especially annoying under Republic or Democratic governance

The invasion of an unguarded enemy city always breaks treaty as I've explained above. As to the latter, I guess it only happens later in the game when the computer controlled civs tend to be more aggressive towards you. Maybe game versions have something to do with this. I play version 3.

 

[Tenochtitlan]

Let me clarify things a little bit:

The situation I've described requires previous contact and the establishment of a peace treaty with the other civilization. Later, when I find an unguarded city and try to capture it, a message appears on the screen asking if I'm sure about breaking the peace treaty. If I select "Yes", I capture the city. The next time I make contact with that civilization (if they possess any remaining cities) they don't treat me as if we were at war. Instead, they act as if we have never met before.

So, I'm talking about breaking peace treaties without the danger of triggering war.

All four cases happened to me but I can't seem to figure out the formula

The four cases are as follows:

You have a peace treaty with another civilization

1. You invade an unguarded city, it breaks the treaty
2. You invade an unguarded city, it doesn't break the treaty
3. They invade your unguarded city, it breaks the treaty
4. They invade your unguarded city, it doesn't break the treaty

Whether or not it breaks the treaty could be because of the attack value on your unit (0 or n), as Urtica dioica theorized

 

[Kunelly83]

I think its when you actually attack a city that is fortified. Even so, makes sure to have a diplomat ready to re-establish peace!