Map display on "Declare war" is incredibly misleading.

[Lessing]

When I declare war, I pick the claim that nets me the most territory, or the best. So when I declared war against the Byzantine Empire, I picked the duchy of Cherson as CB. De jure, that's the duchy just south of Crimea.

The provinces that are surrounded by an extra glow are the ones I actually contest in that war. At least that's what I thought the gist is.

Here you can see everything that glowed. Cherson is region "2". As you can see, there are 6 glowing regions.

When I won that war, I only got region 2 and region 1. I could understand that I only get the de jure parts of the duchy that is in possession by the holder of the CB duke, here the Duke of Cherson.

Then why do I get region 1? And if region 1, why not region 3,4,5 and 6?

How am I to estimate the lands I will gain from pressing a claim if I get some of them, but not all? I can't see the point here of marking provinces I don't get with a glowing outline.

 

[Lessing]

I looked into it some more...... so the area blinks because those are the counties the Duke of Cherson (who is also the Duke of Azon) controls.

He has a vassal who is count of region 3 and region 6. He has another vassal who is count of region 4.

And then he is the liege of a countess who has a county in region 2, and owns region 1.

So when my claimant's claim is pressed, that Duke of Cherson loses the countess as vassal because she moves over to the new duke, my claimant. That means all de jure territories in the duchy of Cherson go over. And because the countess moves over to the new duchy, region 2 follows as well. That is because her main seat is in the duchy of Cherson, I guess.

Because the first two vassals (regions 3,4,6) still remain with the former Duke of Cherson (they had no land in the de jure duchy of Cherson), their counties remains with the Byzantine Empire and their liege, the now Duke of Azov.

Still no clue why Byzantion blinks. Its owned by a count who is vassal to an entirely different duke.

What's the point of marking the duke's territory, when I declare war against the Empire? Wouldnt it be much better to know exactly what territory I will get when the claim is pressed?

 

[BlckKnght]

I've just encountered this same issue. I declared war on the Queen of France over my claim on the Duchy of Aquitaine. That Duchy was held by my Stepfather, who somehow inherited it from his son, my half-brother (who I assassinated), rather than it going to me (my mother was the former Duchess of Aquitaine, and I probably should have assassinated my brother before she died in order to inherit her massive holdings directly).

On the map, the territory highlighted as the duchy of Aquitaine was huge, covering most of southern France, and notably, it was not all of the Duke's territory (his capitol, Dijon was not included, for example). I hired a bunch of Mercenaries and crushed the French armies in several battles, besieged a few territories (the ones I wanted most to claim) and the Queen offered me peace. To my surprise, I got only three territories (one county for myself, and two held by vassals), all within the de jure boundaries of Aquitaine (and mostly not the ones I'd besieged). One territory in the de jure duchy didn't come along. It was a very confusing result.

It would have been much nicer if the highlighted region had shown what territory I would gain from my war! The whole point of it was to connect up a territory one of my family members had inherited within the Duchy of Toulouse, and my war failed to accomplish that. Now I have to wait ten years for my treaty to run out before going to war again, and I'll probably have to keep fighting massive 2k+ rebel outbreaks to keep that territory part of my kingdom in the mean time.

Here's an autosave from just before the end of the war. If you play for a few weeks (winning the lopsided battle that is already underway) the Queen of France will offer peace.

Edit: Here's a screenshot.

I added a blue triangle over the three counties I get in the peace. The red square indicates the one de jure piece of Aquitaine that I don't get (probably because it's owned by a count who's primary title is from La Marche, outside the de jure duchy). The Yellow circled areas are the other duchies owned by the current Duke of Aquitaine. I checked and all of the counties within the highlighted area on the map report that their vassalage is to the duchy of Aquitaine, rather than one of his other titles (I assume this is what the game uses to pick the area to highlight). I think those vassals should come to me, rather than being switching their allegiance to one of the Duke's other Duchies at the end of the war.

Also, if anyone cares to look at my save and tell my why the current Duke of Aquitaine inherited all that land from his son (rather than them going to my character) I'd be interested to know. I hadn't checked the inheritances before assassinating him, but I'd assumed I'd be his heir, since we were half-siblings (and the titles came from our mutual mother). France's Crown Authority is Low, so it's not that.

 

[londoner247]

I don't personally see it as an issue that vassals stick with their liege when he surrenders some of his territory to you. Their feudal relationship is personal rather than to any particular title and I would guess the reason that it appeared to be to his Duchy of Aquitaine title was probably that this was his main title.

I do, however, think it is odd that you don't get the whole Duchy here. The fact that one part is held by somebody else seems irrelevant to me since you declared war on France rather than on an independent Duke of Aquitaine who did not have de facto control of the whole Duchy.

 

[K-vald]

I'm following this up with BlckKnght's save. What I wonder is what exactly the claim was and who the claimant is? Was it a ducal claim (green flag) and so, what was the conditions specified?

Because looking at the peace offering page on the diplomacy page for the Queen of France, it specifically says that your ruler (Queen Elionor I of Aragon) will get the Duchy of Aquitaine and nothing more. However, other terriotires on the map shouldn't be pulsating and I'll look into this.

UPDATE: Tried to declare the war anew but for another duchy, and the pulsating selection worked fine. So once again, what was the conditions for the previous war?

 

[BlckKnght]

I'm pretty sure the war terms were to take "the Duchy of Aquitaine", as my queen has a claim to that title. The trouble is, the game seems to define that duchy differently at war declaration time than it does at peace resolution time.

All of the orange highlighted area in my screenshot is "de facto" part of the Duchy of Aquitaine, both before and during the war. You can see that the counts in it are vassals to Aquitaine by hovering the mouse over the Ducal shield that is next to the french arms on the upper right part of the province display. That land was controlled by the previous dukes of Aquitaine, before the current Duke (who was already Duke of Burgundy) inherited it. Not all of his non-de jure land is part of Aquitaine though (Foix, which is outside of the highlighted area in the screenshot is de facto part of Gascogne).

At the end of the war however, only the de jure duchy's territory gets transferred (or in fact, a bit less, since counts who's primary titles are outside the de jure duchy got to keep their lands inside). The counts who were previously de facto part of Aquitaine become part of Burgundy instead (with the same ruler).

Either interpretation could be valid, though of course I'd favor the "de facto" interpretation. I guess the question is, do the vassals of the current Duke (in his role as Duke of Aquitaine) remain bound to him personally when he gives up that ducal title to somebody else? Or should they become vassals of the new Duke of Aquitaine (in this case, my Queen)? Since neither of us have de jure rights to the land, I'm not sure who should take precedence.

The inconsistency is clearly a bug though. The game should have outlined the de jure duchy if that was going to be all I'd gain in the war.

I do think that de facto ducal territory needs to be conquerable in some way though. My goal in the war was go acquire the counties that are de jure part of Toulouse (which the Dukes of Toulouse haven't held for many years) and link up the isolated county one of my counts inherited (which prior to the latest patch was a big problem due to the bug causing rebels to spawn there endlessly). However, despite having a claim on all of the titles belonging to the previous Dukes of Aquitaine (who had waged war on Toulouse and appointed the ancestors of the current counts), I don't actually have any way to wage a war to get those lands.