I usually tend towards #3 if I'm in a position to do so. Otherwise, I'll go for #4...if they're not receptive to that, #5.

no no no you're supposed to make a separate comment for each one and then ask us to +1 our go-to strategy. Multiple votes allowed. Geesh are you knew here?

Screw that, i don't really want blind poling i want discussion.

Nice change of pace to actually discuss Diplomacy on this forum, no? ;)

You just make us miss the old forum even more..

Free Draug!

As a general matter, I would move defensively to thwart the stab, then follow up after the phase resolves to see why they stabbed. Presumably I'm allied with that power because I think that's best for me, so I want to explore repairing whatever the perceived problem is. My demeanor should be friendly and forgiving of the transgression. If I've done my job right to begin with, the stab attempt should do little or no damage and not really make sense for my ally to have tried in the first place.

This approach keeps in mind that frequently your Intel turns out to be wrong and there is no stab attempt after all. I'd rather not preemptively counterattack or cause a scene when it turns out to have been nothing. There also is game value in being the good ally who forgives your partner's jumpiness instead of the jumpy partner who screwed up with a fizzled stab.

Sometimes:

7. Allow the stab to take place, and use the fact that he stabbed you as leverage with his *other* allies (in the case of multiple alliances) to turn them against him and recover the initiative.

Generally, I go with a combination of #1 and #2. There are two things to note here. First, a stab can often be detected by unusual movements from the year before. Say, if Germany pushes a fleet to Denmark to attack North Sea instead of moving it to Holland or Hel. Second, you should always be prepared for the stab - either be ready to sacrifice any undefended centers, or have units in place to counter one.

I tend to always be communicating with people, even as I'm attacking them. I make light-hearted plans like "well, if the world starts burning around us, lets do x,y,z instead of fighting" That way, I already have a back-up plan in place and am not scrambling frantically once I do see a stab coming.

For no apparent reason, I will have to answer this question in about 15 hours ;)

8. Openly help out the person stabbing you, so he knows you knew in advance and he's only succeeding because you want him to. Then go after his new ally full force so the ally gets nothing out of the alliance shift. In fact he may lose since the stabber is growing and won't need him.

I did this once and my stabber complained that I was taking all the fun out of it. It was a tabletop game and I would tell my stabber which SCs he could have each year. :)

I am not following that #8 suggestion whatsover, you're saying accept the stab and king make him against whoever wanted to ally with him? Sounds more like something you'd do in extreme cases only when it all seems hopeless otherwise, but not sure I'd personally go immediately to that one.

@THM - That's a good one, i've certainly used that type of approach in the past. Never close a door if you can avoid it and try to squeeze every relationship for what it's worth. Stabs happen, don't take them personally.

9. Pray that there is no stab.
If there is a stab, cry.

Depends on the situation. Sometimes it's actually a good idea to treat them with kindness and explain how you're understanding of their dilemma. Once they've decided to halt the advance and redirect their units elsewhere, drive the steel deep into their heart. This is a bit like what The Hanged Man described, except betrayal is intolerable in my book.

If you haven't been planning for this before you hear the rumor, then it's probably already too late.
1. Circling the wagons is the last resort. You can't win if you're reacting instead of dictating, especially if you're reactions are all defensive. Still, there are times where you have no other choice.
2. Start making new alliances? You should already have 1+ other powers who think you're they're primary ally! You should be working on making friends all the time, not just when you think you're going to get stabbed.
3. Only if it's a good stab. And if it's a good stab, then I was going to do it whether or not there were rumors about me being stabbed.
4/5. I spend a lot of time pointing out to my neighbors how they're much better off working with me than stabbing me. Usually, I'll point out a possibility for a stab, then explain how they have more to gain from working with me than by trying to take my centers, as well as how I can hurt them enough to make the stab a poor choice. Sometimes I'll also bluff by saying I'm going to defend a space or center more vigorously than I am actually planning to. If I'm hearing rumors about being stabbed, there's also a good chance that the rumor is there because the power spreading it stands to gain from breaking my alliance, and I'll often turn that against them by telling my ally about how so-and-so is convinced that our alliance won't last, is planning on us falling apart, and that if we stick together, he'll crumble.
6. I've never really figured out how to use global to my advantage. As far as I can tell, most of the good players pretty much ignore it in full press games anyways.

Oh, for 4/5 it also helps if the reasons you're giving your ally are true, or at least plausible. That's where it's important that your tactics and diplomacy align with your strategy.

I first gauge the value of the claim(s). A lot of times, the rumors of a stab are simply untrue and put there by people that just want to see a successful alliance break down.

That said, I have to combine rumors with what I see happening on the board, because the board doesn't lie. Builds don't lie. If I strongly suspect a stab, then I look at moves that will counter.

Not necessarily counter-defend, but counter-strike. It's just as good, and many times better, if I can steal two of his while he steals two of mine than simply defending my two and losing nothing.

Position is everything. I also take time to study how my opponent moves in an effort to try to guess how he will attack. This can help reduce losses or give me a stronger position.

Last, I like to keep a system of checks and balances with others on the board. If I have allies, they can be instrumental in keeping my opponent off-balance.

I laughed so hard when I saw number 6 :)

A lot of the time I can predict a stab by watching builds (usually most helpful when all 3 home SC's, or 4 in Russia's case, are open and they have less than three builds that phase). Fleet v army can get fairly obvious, such as an Austrian fleet build, but also build placement. Army build in Brest can be directly convoyed to Liverpool, while army Paris cannot. On the flipside, Paris can move to burgundy while Brest cannot. It all depends on the situation and is up to you to determine which of several choices are most threatening.

I also like to "play" as other players. Many positions are common and have been played before, making them slightly easier to predict. But if you can imagine yourself playing as another country, you can see their priorities and what tactics they would use to attack.

In my experience, you can't go wrong with tactical nukes.

Oh right, that reminds me. I just ran out after that last gunboat. Let me go to the store to get more. Plutonium or uranium?

Speaking of gunboats, I'm sure Kim Jong Un would rather that than full press (if they can even play board games over there). He's working on having nukes be his mode of negotiation rather than words. Words ARE more dangerous than nukes you know.

Most the time my first go-to reaction is to try to alter the appeal of the stab. Sometimes that means an outright (yet gentle) confrontation and sometimes it's just a subtle hint alluding that my guard is likely to be up for the next round. They important thing is to make sure that it's clear that the element of surprise is no longer there and the stab may not pay off quite as well as they hoped. If you can pull that off while allowing them to feel comfortable that harm no foul. Somehow plant in there that your guard was up due to something a potential new partner for your ally may have done (betrayed, incompetently tipped you off, whatever) then even better.

If that doesn't do the trick and the stab moves forward then keep calm and carry on. You gain little by freaking out and burning a bridge, better to start figuring out over ways to spin this. Some really great blindsides come right after a stab, very few people see those coming and if you're a good enough diplomat to smooth things over fast enough it's actually pretty easy to sell a nice counter-stab since you've got the pre-existing relationship and everybody loves to be part of a good "shocking moment" in the game.

Of course sometimes you just know the stabber well enough to know the stab was always going to come and was just a matter of time, in those instances just best to keep quite and play dumb and prepare as best you with side alliances and counter-attacks.