This article is considered accurate for the current version of the game.
- 1 Forming a personal union
- 2 Effect
- 3 Ending a personal union
- 4 Special cases
Forming a personal union
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There are two diplomatic actions which can lead to a personal union.
Royal marriage: If two countries have [needs verification] and a royal marriage and the ruler in one of the nations dies without an heir, the other country will gain a personal union if it has higher prestige than any other same dynasty nations. If someone contests this, a succession war will follow. It is vital to do a royal marriage when you have high prestige, as this is taken into account to determine whether or not your noble succeeds to the throne of the target heirless nation. Note that's it is possible to get a personal union with a succession war even without having same dynasty as the heirless nation. Player nation needs a powerful rival then that is willing to start a succession war over the right to install your noble on the throne of the target nation. At the start of the war the target nation will become your subject.
Claim throne: If you have a royal marriage with a nation that has same dynasty ruler, and they have a disputed succession (either no heir or an heir with low legitimacy) (weak claim), you can take the diplomatic action to claim their throne. Taking this action will give a -50 relations penalty to all countries you have a royal marriage with, including the -100 penalty with the target. The biggest benefit from claiming a throne is that it gives you a claim throne casus belli to force the target country into a personal union for 84% warscore, rather than hoping their king will die without an heir. Since this casus belli always costs 84% warscore, regardless of size, it's one of the best ways to gain large swathes of territory for little cost. This casus belli disappears if the target heirless nation gets a strong heir.
There are 6 possible situations for a nation that has disputed succession. All 6 can have different outcome, depending whether or not the player decides to step into the game of obtaining personal unions.
- No dynasty, no heir
- No dynasty, weak heir / regency
- Same dynasty, no heir
- Same dynasty, weak heir / regency
- Succession war as defender/attacker
- Inheritance the nation
No dynasty, no heir
- The player does not share a dynasty with target nation. They have no heir.
If the target nation' ruler dies without an heir, there is chance to get a personal union with a succession war, if a rival of the player nation or the target nation qualifies to contest the right to have the nation as minor personal union subject.
The goal is to put your dynasty on the throne of a foreign nation to open up future possibilities, or to get succession wars over heirless nations.
The player can send "royal marriage" offers and later on "offer alliance" offers to two greater power nations at once in 1444, sending two diplomats on the same day, after meeting the requirements of the target nations involved. An example would be to offer alliance to Burgundy and Castile on the same day, with 2 diplomats, to avoid the acceptance malus for having multiple greater power nations as ally. Note that it is possible to have three or more greater powers as ally, if the range to them is low enough to secure a royal marriage and if player' nation has a lot of positive opinion modifiers with them. The greater powers might send offer alliance proposals to the player after using your diplomats to improve relations. This way, it is possible to have alliances with many greater power nations at once.
Whatever nation married the nation first, has more chance of delivering an heir of their dynasty to the nation. Note that the prestige value at the time of the marriage is important too. If a real big nation married them first, the player has little chance though, even with maxed prestige. But: the player can get succession wars more often with a royal marriage done at high prestige and a noble of the player' dynasty has lot more chance to succeed to a foreign throne if an heirless king dies, if no real big nation did royal marriage with the heirless country.
So, get prestige to 100 and do royal marriage to target nation and pray that a noble of the player nation succeeds to a foreign throne, or that an easy succession war occurs for the heirless nation upon their ruler' demise.
To get succession wars in step A, it is VITAL the player nation sets a powerful nation as rival. Muscovy or France will do. If not, its impossible to get succession wars in this stage. Note that it is entirely possible to get succession wars over a nation with no heir -that is NOT of your dynasty but with whom the player nation has a royal marriage with- IF there is a greater power nation willing to aggressively contest the succession.
A noble of the player nation will become the king of the target nation IF
- If player nation married the country FIRST before all others and/or
- If player nation had highest prestige of all royal marriage partners of that nation when the royal marriage was asked
- If no greater power nation can contest the succession in any way, as stated above.
"a xxxxyan noble succeeds to the throne" it will say, looking at what the outcome of succession will be, in the target nation' diplomacy window. If they produce an heir, chances for this are removed. The player may not start a war to create a union, until step C.
If the heirless king dies, a noble of the player nation will succeed to their throne if
- If no succession war can trigger and
- If the player nation had higher prestige then other royal marriage partners when the royal marriage was asked. If not, hope the ruler with whom they did royal marriage first dies; which will make the player nation' royal marriage the oldest.
The aggressive claimant of the disputed succession can change each month: usually it as a rival of the player nation, but it can also be another nation of the player nation' dynasty, if the target country is of your dynasty.
The succession status itself will shift from succession war to a noble becoming king if target heirless nation goes to war. It is good idea to warn the target heirless nation not to go to war.
Important note: after a noble of player nation' dynasty took throne, it is recommended to break royal marriage if target nation is not an ally, to regain the diplomacy slot. The player nation can get succession war over a same dynasty nation when their ruler dies heirless, even without an active royal marriage with them. The player can hope for a succession war in the rest of the game, regarding this nation. This is why being papal controller is a useful tool in game of thrones: the player can break royal marriages at will without stability hit, once the desired dynasty spread to the nation involved is obtained.
Important note: most players assume their current prestige matters for disputed succession when they did royal marriage with a nation. This is incorrect. The prestige the player nation' had when asking for royal marriage is what counts. So try to obtain royal marriages with greater powers and heirless countries, when your prestige is maxed. This increases the chance to get succession war with a rival over the target heirless nation. It also makes the player favorite to install a noble on the throne of the target nation, if their ruler dies without an heir. If the rival that will attack in a succession war is a lot weaker then the player nation, he might back down, giving you the personal union with he target nation for free without a war.
No dynasty, weak heir / regency
- The player does not share a dynasty with target nation. They have a weak heir.
Basically, do nothing in this situation.
Same dynasty, no heir
- The player shares dynasty with target nation. They have no heir.
The player can use the claim throne action in diplomacy window of the target nation if he has more prestige then the target nation. The player receives casus belli to start a war to force a personal union. If the ruler dies and the heir ascends or if the ruler gets a strong heir, the player will lose the casus belli and the claim to the throne, if he did not start the war. If the player nation can win a war, claim the throne and use the casus belli to force a personal union. If winning a war would be hard, then try to become highest prestige same dynasty nation and hope for succession war. Or, claim throne and hope that target nation does not get an heir before the ruler dies. If the heirless ruler dies heirless after you claimed, you usually get the personal union.
If the player nation has the same dynasty as the target nation and no royal marriage with them: if they are highest prestige country of all dynasty partners, then it is possible to get a succession war over the target country, with the player nation as defender. Note that, for succession war to trigger, it is not needed to have a royal marriage with heirless nation , if the target nation is of same dynasty. Setting a powerful rival is vital for this.
If the heirless ruler dies without an heir, the player gets a personal union, right of the bat, no war involved, if:
- 1.) The target nation is a small country with same dynasty and the player nation has a royal marriage with the target nation. The ruler of the target nation dies heirless.
- 2.) The player nation has no royal marriage with target nation who has a ruler of same dynasty as the player nation. The diplomacy window of target nation shows that a succession war will trigger on the demise of the heirless ruler. The aggressive claimant in the succession war is a lot weaker then the player. They can back down then, giving the player the personal union with the target nation for free.
Note that in option c there is no way for other royal marriage partners (of the heirless nation that aren't dynasty partners), to get this personal union. Nations can unrightfully contest this succession outcome if: the nation is a rival of the player nation; the nation also has the same dynasty as the player nation; they are greater power nation and an ally of the target nation. The player nation needs to be rival of the nation who normally would get the personal union, to qualify to unrightfully (as in aggressively through popup) contest this outcome of a succession.
An example of a peaceful transition: Nation A has a ruler of same dynasty as nation B, nation B' ruler dies heirless, and nation B has a royal marriage with nation A. If the ruler of the target nation dies heirless, then nation B becomes minor personal union subject of nation A. Usually a peaceful transition is done between a big country and a really small country that is close to them. Example: Muscovy getting peaceful personal union over Ryazan.
An example of an enemy of the heirless country being able to contest succession without having royal marriage: Poland spread its dynasty to Muscovy. The king of Muscovy dies without an heir. Poland is rightful claimant, due to having royal marriage with dynasty member, but Sweden can contest this, since they are a rival of Poland. Succession war will decide if Muscovy goes under Poland or Sweden as minor PU slave.
Same dynasty, weak heir / regency
- The player shares dynasty with target nation. They have a weak heir/regency.
The player can use the claim throne action in diplomacy window of the target nation if he has more prestige then the target nation. The player receives casus belli to start a war to force a union. If the ruler dies and the heir ascends or if the ruler gets a strong heir, the player will lose the casus belli and the claim to the throne, if he did not start the war. If player nation can win a war, then use the claim throne button in the diplomacy window of the target heirless nation, and use the casus belli to force a personal union.
Succession war as defender/attacker
- The player nation and a third nation qualify for succession war.
A succession war can trigger if there are 2 sides who can contest the succession meaning:
- The rightful royal marriage/dynasty claimant (rightful meaning as in: they got royal marriage and/or same dynasty with heirless nation; or they don't have royal marriage with the heirless nation but they got highest prestige of all dynasty partners)
- The aggressive claimant (meaning they are rivals of the rightful claimant) that qualify to get involved in a succession war.
A succession war erupts if the ruler of the target nation dies heirless, and if two nations qualify to wage succession war. The most powerful country that can contest the succession outcome aggressively will get popup if they want to enforce their aggressive claim with a war. This means that if the player is the rightful claimant, your rival might declare war to take the freshly installed personal union away from the player for their own. And there will be no popup, the succession war will start whenever the involved heirless king dies. There is no way for the player to avoid this war. If the player qualifies to contest that their rival places a noble of their dynasty on a foreign throne, a pop up will appear asking the player whether or not he wants to aggressively contest the succession.
What happens next?
- The DEFENDER (the rightful claimant) gets the target nation as a personal union subject at the start of the war, but the player, his allies, and the new subject nation need to fight a rival nation/other claimant over the right to have the nation as a minor personal union subject. All the allies of both sides can get call to war when this aggressive claimant declares war on the player.
- The ATTACKER needs to fight the defender nation, the target nation who will be subject to them and all their allies. This attacker can call in their allies in this situation too.
If defender, the player nation will go to war when heirless ruler dies of the target nation. If the player gets the popup to choose to contest the succession: only attack if player nation and their allies can win war against heirless nation, the nation that gets the target nation as subject and it's allies, otherwise don't press.
You inherit the throne
The player nation inherits the target nation, bypassing a personal union completely. The player will simply absorb the target nation and receive immediate cores on all their provinces and their colonial nations become yours. Their vassals will be set free. Possible situations this can happen: the player has same dynasty as them and high prestige. There are a lot of other ways too. If the target heirless nation is small enough versus the player nation, there is chance for inheritance. The player nation gets cores on all their provinces and the nation will seize to exist.
- The game of thrones in Europe and beyond is lot more complex then just disputed succession. This game of thrones is the hidden aspect of this game, that nevertheless can give the player the most territory gain for a world conquest attempt.
- Playing the claim throne and royal marriage game means keeping prestige at near hundred all the time, never giving in to rebels. The player has to adapt their gameplay: keep conquest and rebels balanced. Humanism is a great idea group to prevent rebel problems on non accepted culture provinces.
- A nation can grow strong when they gain a personal union with a greater power nation. Like France getting Castile as minor personal union subject. Play this game, and Castile could have been the player' personal union subject. What the AI can do, so can the player.
- important tip: message settings are crucial for this game of thrones. First and foremost, and this might be the most neglected aspect of eu4. Hidden popup and pause messages that the player can enable, that are off by default. In message settings select "all" tab and enable the popup and pause for every herald possible for *every option" in the "to me", "from me", "interesting" and "other" categories.. Then, in the window above the map buttons select interesting nations. In short: select all nations in the religion group of the player nation, since the player nation can't get personal union over a nation that is not in their religion group. The result is that the player can perfectly see when a new king comes to power, or when an event takes place that kills an heir of a nation.
Example: Enable minor and major event popup and pause for interesting countries, for any event they get. Why? If that interesting country has 40+ king with a regency heir for example, and the target country gets the event that might kill their heir, the player can see the outcome right after. No more AI personal unions being installed without the player having a clue.
The player can then later disable the popup and pause for unnecessary message types (like what country gives military access to another) by changing it in the popup window (options at right bottom). Some important popups the player should enable for popup and pause: when armies arrive at destination, when country gets new king, major and minor events for any nation, diplomats arriving back home, traders arriving back home, what country gets succession war with another, when a country starts integrating a vassal and so on and so forth. Prepare to read ton of stuff, the player can disable this but might miss out on easy dynasty spread chances when a country' heir dies due to event.
- Note that an heir of a country can die during combat, sieging or just of natural cause as well, and the player will not receive a herald popup and pause for this. Here comes the disputed succession window in handy, to check if there is any heir dead (that a country went to disputed succession status without you getting notice from herald). Prepare to look at diplomacy of many countries frequently, or its easy to miss out on easy RM and dynasty spread partners.
NB: since 1.2 the CB is now only granted when claiming the throne of a country with the same dynasty as yours.
NB: since 1.7 You can only claim the throne of a country that is the same dynasty as yours.
A personal union is similar to vassalage. The senior partner controls the diplomacy of the junior partner and the junior partner will always join their wars. The junior partner cannot declare war, negotiate separate peace treaties or enter royal marriages. As in vassalage, being the senior partner of an elector in the Holy Roman Empire will result in a 50 point bonus to their electoral vote and a 50 point malus from all non controlled electors.
However, unlike a vassal, you do not receive any income from lesser partners in a personal union.
Ending a personal union
A personal union can end in several ways. Either with the incorporation of the junior partner in the senior partner,with the junior partner declaring their independence, with negative prestige number when your current ruler dies, with negative opinion modifier of the target nation when your current ruler dies, with pretender rebels enforcing their demands in the target nation.
Integration & inheritance
After 50 years the senior partner can inherit or integrate the junior partner. Inheriting is random if the target nation is small enough versus yours; it has a chance to occur each time the ruler dies. This chance may be 0%; to see the probability, hover over the king in the diplomacy screen. The chance mainly depends on two factors: the Diplomatic Reputation of the senior partner and the base tax of the junior partner. Because of this, large countries can never be inherited. The Stability of the senior partner also plays a role in this chance, but only a minor one.
Alternatively, if the senior partner has over 190 relations with their junior partner, they can take the diplomatic action "Integrate" to immediately start the process of integrating them. This process works identically to annexing a vassal: it will take one month and 15 diplomatic power per point of base tax of the junior partner, and the diplomat cannot perform any other missions while integrating. You may cancel the diplomat, but all progress and diplomatic power will be lost, so this is generally not recommended. To see the modifiers, progress, and remaining time, hover over the icon in the diplomacy screen or in the outliner once integration has started. Either way, integration will end with the senior partner owning all the junior partner's territory and gaining cores on all their provinces - even the ones the junior partner themselves didn't have cores on - as well as being the new overlord of any vassals, protectorates, or colonial nations the junior partner may have had.
Rebels that change government type or state religion and enforce their demands in the provinces of the junior partner being integrated may instantly cancel the annexation process and even break the Personal Union.
Note: Player-controlled nations will never be inherited on monarch death, though they may still be integrated manually by their overlord.
If the senior partner's king dies while having negative prestige or negative relations with the junior partner, the junior partner will become an independent nation again and be assigned a new king of your dynasty. The senior partner will get a "Restoration of Union" casus belli to reclaim the throne for 60% warscore. A junior partner can also declare war on their senior partner at any time - even while the nations are in a war together (since the 1.6 patch) - to gain their independence. Note that, since the 1.6 patch, a "great power" nation which is the lesser partner in a personal union is far more likely to declare a war for independence. If you manage to keep their opinion at +200, then they will ever declare independence. Once you are big enough versus them they will never declare independence.
If the country creates personal union as a leader with another country which is leading its own personal union, also the junior partner's junior partner will enter the personal union. Example: Aragon is leading personal union with Naples and Castile creates personal union with Aragon as a leader, Castile will lead personal union with both Aragon and Naples.