But - whats the price? If there is no price, a player could just start by saying:
"Nothing personal guys, but I'm declaring war on everybody, just to get it out of the way. Will be diploming as usual".

I like casi belli (reminds me of Europa Universalis, which is a good thing), but they have to involve some kind of price. Maybe only declare war with only ONE player at a time? But if you don't involve neutrals, this is still a pretty limited restriction.

I don't think players would do that, because then they could be attacked by everyone at once. For example, as Austria, declaring war on everybody is suicide, especially if those other players don't have any other wars ongoing - meaning they can ONLY attack neutral territories and Austria.

How about this, a proper alliance button which you both can click to form alliance, and if you declare war on one, the other can also attack you (but you are unaware of this before declaring war). So you declare war on Germany and it comes up "Austria has declared war on Germany and Italy", and only then do you realise that they are allied.

And perhaps only allow players to have 1 alliance at a time.

Yeah, good to tie in with alliances. You should also do that you have to break alliances before declaring war, giving people lag before they can attack that person.

Having said that, you still need some kind of carrot/stick. What do people gain from making a formal alliance? What do people lose when declaring war? You say they *can* be attacked by anyone. But truth is, that is already the case since they can just declare war at the drop of a hat.

You could only allow 1 declaration of war or alteration of alliances per year. That would make the whole system a lot more strategic.

"For example, as Austria, declaring war on everybody is suicide, especially if those other players don't have any other wars ongoing - meaning they can ONLY attack neutral territories and Austria. "

No, they can attack anyone, because they can declare war on anyone whenever they want.

To be clear, the cost is that if you declare war you lose negotiating position. Anyone you want as an ally you don't declare war on, as a sign of good-will.

The question is when you have to declare war, if at the start of the turn, or before? Can you wait until the last second before your moves go through?

I declaration of war or alliance makes for a completely different setup.

Can i defend my allies by moving a unit to protect their supply centers? or would this be seen as an attack and thus be prevented by the code??

I agree with orathaic, the cost of declaring war is that you can no longer tell a person that you won't attack them. By not declaring war on someone, you gain trust because the other country knows you are not going to directly attack them. You may indirectly attack them through supporting someone else or not giving support you said you would, but knowing you can't directly attack them has value. Declaring war costs that value.

orathaic, as for the timing, I would think it would need to be setup for example for a 48 hour/phase game, the first 24 hours of a phase you can declare war, and the second 24 hours of the phase you cannot.

I wonder about the whole "player’s territories" and "no restrictions on neutral territories, even if they have units in them during the spring turn". Currently the webdip code gives neutral non-SC territories in the Spring. For example, Austria moves to Albania and Serbia in the Spring. Albania is shaded Austria's color while Serbia is not. Do non-SC territories start to follow the SC rules where they are only captured in the Autumn? I would be tempted to go the other route and instead disallow attacking a neutral territory that another player is in in the Spring but doesn't yet officially own without having declared war on that player.

What about forcing declarations of war in spring, and banning them from Fall, so you can 'attack' in spring turn, but not take SC.

but perhaps that should be with crystal ball variant where you have to enter moves one turn in advance...