Using Open Borders to launch an attack on a third party

I knew this was possible, but I only just tried it in my last game.

I want to do a overseas invasion of another continent. We're at the Frigates & Galleons level of tech, so it takes a while to drag a decent army across the ocean. I could build six or eight Galleons but that seems sort of wasteful.

The other continent has two civs, Mansa and Gandhi. I have Open Borders with them both.

So I ferried my army -- fifteen units or so -- to Gandhi's territory, and then launched an attack from there.

This works surprisingly well. Not only does it solve the invasion problem, but Gandhi's cultural pressure means that several of Mansa's cities are just a couple of squares from the border. I was able to gain complete operational surprise.

Now, I want to destroy Mansa, not conquer him -- I'm only going to save one or two of his cities. In this situation, there's another bonus: once a border city is captured, I just raze it and then roll back across the border. I can use Gandhi's road network to zoom back and forth.

Gandhi doesn't seem to mind that I'm using his territory to attack his friend, and Mansa doesn't seem annoyed with Gandhi. Go figure. I guess the AI can't take these fine points into account.

Is this a common tactic?


Waldo

Hell, the AIs do that sort of thing against me all the time (except less well and generally not overseas). Open borders are open borders.

Just watch the diplomatic relations between your target and other civs. I used another civ once, but I didn't check the diplomatic screen. The open borders civ cancelled the deal on his turn. This had a few bad side effect:

1. All of my units in transit were bumped out. This made for a logistical nightmare getting them to the war.

2. My units that had great defensive positions in border tiles were bumped to not-so-great tiles in the enemy territory.

3. My target civ still had an open border agreement with the other civ, and was able to launch attacks from multiple sides.

I always make sure that my open border civ is on bad terms with my target civ.

------------------------------------

On a different topic, I have had an open border agreement with my target civ. I landed troops, marched to neutral ground, then launched my attack.

chicagocubs is right, it's a lot better if your landing zone isn't open to the Ai you wish to attack.
This way you can just go back for healing, without second thought.

On my current game, I did just this, using my OB with Yahya of Yemen to surround Mehmed of Turkey and attack him from two (later, three) different directions.

(Those unfamiliar with the names should note I'm running CivGold.)

ChicagoCubs - excellent point.

This can work, but IMHO it's preferable to do an amphibious attack for your opening shot in a long-distance war, using ships to lower the target city defenses. If you just take the first city on the border with your open borders partner, you also have to worry about his culture messing up your new territory -- cities can still flip to a third-party civ after conquest. You also risk what happened to Chicagocubs. (Make sure that your target and your OB friend aren't good pals first...or, worse, have a defense pact!)

I have my own story, although it was minor and didn't have any real impact on the rest of the war:

Playing as Rome on SevoMod, I'd turned into the juggernaut of the game and beginning my expansion into the northern half of the continent (I had already conquered and incorporated Mali and the Vikings into my empire). Anyways, although I had a direct border with Carthage, who I was invading, a good half of the space between us was occupied by Persia (who I had invaded earlier but had OB with again). Anyways, Carthage tried to launch its counter-attack into Rome through Persian territory, but I had stationed some tanks at the border in case this happened. There ended up being a pretty big battle right smack-dab in the middle of Cyrus' territory, and although I won, he canceled Open Borders with me the next turn (and didn't with Hannibal...)

Hmm, a thought occured to me: do AIs refuse to talk with other AIs after having deals cancelled on them, as is the case with human players?

It's just that I suspect the cancellation of OB is more often a result of the victim asking the other AI to close deals with you, rather than a drop in relation modifiers.
In that case bribing the third party to cancel deals first would remove the possibility of the victim doing the same, since they'll refuse to talk to one-another for a bit (and that 'Refuses to talk' thing can last for quite a while from what I've seen) Ergo: no chance of OB suddenly being dropped, or at least not until you've secured some territory...

Again, I've no idea whether this takes effect among AIs though so this might not work.
I wouldn't know how to verify this scenario either because 'refuses to talk' doesn't show on the diplomacy screen. Hence, one can't tell whether it's in effect between two other civs... AFAIK at least.

JoeBlade said:

In that case bribing the third party to cancel deals first would remove the possibility of the victim doing the same, since they'll refuse to talk to one-another for a bit (and that 'Refuses to talk' thing can last for quite a while from what I've seen) Ergo: no chance of OB suddenly being dropped, or at least not until you've secured some territory...

Click to expand...

Good point. It would be worthwhile spending tech/gold on this rather than spending so many hammers on a massive fleet and reinforcements after an assault on the target directly. Even change religion. Razing the border cities seems the best idea too.

*ALWAYS* pay your launching pad to cancel trade with your victim just before you declare war on the victim. This does a few things:

1. Forces the victims troops out - sometimes to the side of your launching pad's territory that's *away* from your victims! Always funny to see a pile of troops stuck out somewhere being useless.

2. Hurts the victims opinion of the launching pad, making it less likely they'll get into cahoots anytime soon.

3. As mentioned above, dramatically reduces the chances that the victim will demand that your launching pad cancel OB with you.

Morgrad said:

*ALWAYS* pay your launching pad to cancel trade with your victim just before you declare war on the victim.

Click to expand...

Unfortunately, you don't always have that option, unless you've been deliberately managing relations with the 'launch pad' civ with this long-distance war in mind (i.e., giving in to requests, adopting favorite civic/religion.) This is another reason why I prefer relying on amphibious attacks. (And if you're fighting a long-distance war, you really can't have too many ships -- even if it's relatively early and they're just frigates. Especially when playing using BETTER AI.)

Well, I assumed people know that "ALWAYS" in Civ terms means "ALWAYS (where possible)". One of the things I like about this game is that enemy civs don't behave the way you'd like them to, even when you think they should.

Morgrad said:

Well, I assumed people know that "ALWAYS" in Civ terms means "ALWAYS (where possible)". One of the things I like about this game is that enemy civs don't behave the way you'd like them to, even when you think they should.

Click to expand...

I think "*ALWAYS*" with two asterisks around it implies a vice-like commitment to ALWAYS do something.

What's funny is attacking from the territory of another civ where you have open borders and your opponent does not. With troops right on the cultural boundaries, you can attack them and they cannot do so back at you.

Very nice if they happen to have a city that has cultural pressure from your open-borders friend and the boundaries go right up to the city itself. You can park troops right outside the city (in your friend's territory) and not fear any attacks or counter-attacks from the city under siege.

Question - does this situation apply to planes in anyone's experience? In other words, if I have a stack in a territory where my opponent does not have open borders (and is not at war), can they still bomb that stack?

Be careful in relying on open borders. I was doing this very same tactic once, against the Chinese. I put my airforce and attack stack in a friendly city, a few squares from the targeted Chinese city. When I moved my attack stack to conquer the Chinese city, somewhere along the line he also signed open borders with the same third party, used the third party's railroads, and... well, planes don't defend too well on the ground.

At least China paid dearly for that one.

Kev said:

What's funny is attacking from the territory of another civ where you have open borders and your opponent does not. With troops right on the cultural boundaries, you can attack them and they cannot do so back at you.

Very nice if they happen to have a city that has cultural pressure from your open-borders friend and the boundaries go right up to the city itself. You can park troops right outside the city (in your friend's territory) and not fear any attacks or counter-attacks from the city under siege.

Question - does this situation apply to planes in anyone's experience? In other words, if I have a stack in a territory where my opponent does not have open borders (and is not at war), can they still bomb that stack?

Click to expand...

IIRC, only if they declare war on the civ who owns the territory.

Also, in your scenario, you need to worry about cultural pressure from your 'ally' once you take the targeted city.

Well using diplomacy for attacks doesnt stop with open borders. Its often far cheaper, diplomatically, for the military effect of convincing ghandi to stop trading with him for a few turns, maybe to convert to a different religion, and then in fact help you in warring with him. This not only destroys mansa but it gives you a nice powerful ally in ghandi, which would later be useful for, say, a diplomatic victory. Long term plans are always tangled into this stuff.