AI sneak attack detection and prevention

[solo]

Having played many games where it was in my best interest to maintain peaceful relations with the AI, I have been working on some ideas to help predict and prevent AI sneak attacks. I would appreciate any input from others who have played several games where diplomatic rather than forceful strategies were used to help prevent AI sneak attacks. My observations and opinions based on them are listed below, and fall into 2 categories, detection and prevention:


REASONS OR INDICATORS THAT AN AI SNEAK ATTACK MAY BE COMING

1) First and most obvious is the massing of military units just outside one’s borders. By the time this is noticed, the AI’s decision to attack has been finalized and attempts to avoid the attack are usually futile.

2) A more subtle indicator that something is up may be the lack of activity by neighboring AI workers that usually precedes 1) above.

3) Having fewer units can invite an attack, but oddly enough, this does not seem to be a prime consideration. I have played well into the Industrial Age in many OCC games at deity level with only 3 warriors defending my only city. In games where I was attacked, it was early on, and I was sharing a small continent or an island with just one AI. This leads to 3) below:

4) If you are the only convenient target, your proximity makes you more susceptible to a sneak attack. If a neighboring AI has just finished conquering the rest of your continent, an undeniable pattern of behavior has been established.

5) A length of time without any communications between you and an AI will increase the odds of a sneak attack.

6) If you drive hard bargains in trade deals, you are more apt to become a target. Deals which are fair or favorable to the AI decrease the odds of a sneak attack.

7) Changes in an AI’s trading behavior are good indicators. A reluctance to accept deals with per/turn payments should send up red flags. Conversely, an AI that agrees to a deal that is unusually profitable for you is another indicator. For example, suddenly you are able to charge 90 gold/turn for a tech the other AI will only pay 15 to 20 gold/turn for.

8) Most sneak attacks come from AI’s who are “polite” or “gracious” and who have been this way for quite a long time. Once “gracious”, you can’t make them like you any better. I have yet to be attacked by an AI in the period after improving its attitude upwards with a favorable trade or gift.

9) When demands are made, paying tribute does not seem to increase the odds of a sneak attack later. Refusing it, on the other hand, entails the risk of immediate conflict.

10) If you just beat a neighboring AI to a wonder it was building and it can not switch to another, a sneak attack may follow a few turns later.

11) The same goes for espionage. Curiously, sneak attacks are more likely after a lot of successful snooping. Don’t believe that all the spying was “not detected.”

12) An AI without a map is less likely to attack. I used to believe they never attacked without getting a map first, but received a rude awakening in one game, in which I was attacked when I was sure I had not traded any maps away. However, it could be that that AI managed enough cartography with a passing galley or wandering settler earlier in the game.

13) An inadvertent action, taken as a double-cross by an AI, can lead to a sneak attack later. An example would be if you negotiate a peace treaty with a common enemy. Your MPP partner will take this as a betrayal and attack you later. However, this falls more into the category of retaliatory attacks. This thread is specifically dealing with totally unprovoked attacks that are meant to come as a complete surprise.


THINGS THAT LESSEN THE ODDS OF AN AI SNEAK ATTACK

1) It can be dangerous starting the game with just one AI on your island or continent, because if they are aggressive, the local barbarians won’t be getting all of their attention. Best bet is to add some extra cheap units, early. Workers are a good choice, since they can be put to use, are not seen as a threat by your neighbor, and can be added back into your cities later on. Another good early move might be to establish an embassy and to trade with this AI. Once contact is made with other AI, chances of an early sneak attack from this immediate neighbor drop significantly.

2) Maintain communications. Try to talk at least once every 15 turns, or so. If you have nothing to trade or discuss, just present a small gift of gold.

3) When you are contacted about an unwanted deal, such as a ROP agreement, come up with an alternative. If there is not anything you want to do, a small gift of gold will suffice in order to conclude the session in an agreeable way without giving the AI what they asked for.

4) Engage in as much trade as possible. The more each AI see you as a valuable trading partner, the less likely they are to attack. If you are paying gold for something, try to include 1 gold/turn as part of the deal. An AI receiving income from you on a per/turn basis is less likely to cut off these payments voluntarily.

5) Along these lines, it helps to use imported luxuries to maintain happiness, and to depend less on beating the AI to the happiness wonders. Export all strategic resources, not just extra copies, to get the AI to depend on you even more for their supplies. Import any resource you lost use of this way from another AI who has an extra.

6) There is no need to just settle for what an AI will offer in a trade, but it will be a mistake to get too greedy. Any deal that ends with the AI commenting that it was “hard bargain” is probably best followed with an immediate gift of 10 gold or more to conclude the session on a more happy note.

7) The AI will not cancel any 20 turn deal that they think is a good one for them. “Depriving” you of the use of your only copy of saltpeter that you are exporting to them, or letting them continue to import gems for only 5 gold/turn when you could be demanding 20, are the kind of enduring trades that they will hesitate to cancel by suddenly declaring war.

8) Avoid trading your own maps, at least until everyone has made contact with everyone else. An AI is more likely to attack targets they can “see.” Unfortunately, the AI will demand maps when extorting tribute. However these demands usually follow a period of no diplomatic activity, so keep communications open.

9) Try to keep AI attitudes from reaching either extreme. Gifts of 10 gold increments can be used to raise their attitudes. Sometimes it takes more than 10 gold to hit the next level up. The best and most predictable kind of AI are the ones you always need to bump up from “annoyed” to “cautious” or “polite” during each trading session. It’s the ones the remain “polite” or become “gracious” that have to be watched.

10) In conclusion, the best way to avoid sneak attacks is by making other targets seem more desirable. If an AI war ends with an AI being wiped out, leaving you as the next convenient target, it is probably the time to establish an MPP and stick with it for the rest of the game.

11) Oh, and if an AI suddenly masses along your border in spite of the preventative measures taken above, one thing that worked for me once was a hefty per turn gold deal in that AI’s favor.

[Harovan]

I would like to add an indicator:

AI's, who were former allies or MPP/RoP partners and "regrettable don't want to continue the deal" even if you add a reasonable amount of money, are most likely to attack you within a few turns.

[Allemand]

Some very good advice. Thanks.

[Arrian]

In the early game, it is crucial that you connect your roads to the AI's so you can trade. In my experience, the best way to prevent an early attack by an AI is to trade a luxury to that civ for whatever they offer (no haggling). That usually results in a shift from "annoyed" to "polite." Basically, they envy your resouces... but if you trade with them for a good price, they are fine with it. Later, when you're more powerful, start haggling. Since you now have a trade history with them and they are polite with you, haggling doesn't hurt you (much). If you haggle w/an "annoyed" civ, they will most likely stay annoyed.

Taking a border city by culture seems to increase the chances for a sneak attack, as well. But I could be wrong on this one.

Disbanding a city that you took by culture will really piss off the civ it used to belong to.

I admit, there have been many times where AI sneak attacks have totally surprised me. Never saw 'em coming. Of course, those tended to be the most ridiculous and ill-advised ones, too.
Example:

Monarch, Continents, 8 civs. I have my own island, after wiping out my neighbors (I forget who they were). The English have their own island, as do the Iroquois. I have 2 luxuries, the English have 2, the Iroquois have 1. I ponder the situation, noting that the Iroquois are quite weak compared to the English, and so I decide to take out the Iroquois. I load up 4 galleons with Knights and sail over. The turn before I am about to land my force and declare war, the English land a stack (pikeman, warrior, archer, I think) on my land, and declare war when asked to leave. *Boggle* So I crushed them instead (worked out great for me - 2 luxuries gained instead of one).

-Arrian

[Bautou]

I've noticed that often the AI will sneak-attack you when you're militarily superior if your forces are heavily concentrated away from your border that civ.

For me, the situation is usually something like this: I'm fighting the evil civ X on my northern border, towards the end of the war (or shortly thereafter) most of my offensive units are in the north, and compared to civ Y on my southern border I have an equal or bigger army according the military advisor. However, a very good portion of the time civ Y will take this opportunity to launch their attack.

If I spread my forces out (even if I don't place them near the southern border) then the AI seems much less willing to attack. That being said, I think that AI sneak attacks are pretty easy to foil if you can open up a two front war against it.

One time, the AI had me on the ropes with a nasty sneak attack and probably could have reached my capital before I could bring in reinforcements. However, I signed a military alliance with a smaller civ (the Zulus) along the enemy civ's opposite border, and all of a sudden like magic, the massive AI army that could have easily taken more than a few of my cities in that one turn, turned around and marched back into its own territory (presumably to capture some easy Zulu cities on the other side of the map). The enemy civ crushed the Zulus before that big army even reached that front, by which time I had my own big army in place to attack. It could have been a nasty fight, but the AI has too much trouble with a two front war to be much of a challenge.