Personal union

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This article may contain outdated information that is inaccurate for the current version of the game. It was last updated for Vanilla.

Personal union.png
personal union is a form of diplomatic relationship where one monarch rules over two countries. It can be formed by having a royal marriage with a monarch who dies without an heir or if a monarch of the same dynasty dies with out an heir. It may also be formed by enforcing a claim through war or, in certain countries, through an event or decision. Once formed, it works similar to vassalage: the country leading the union (the senior partner) gains the throne and dominates the country who lost their monarch, (the junior partner).

Forming a personal union[edit]

There are two diplomatic actions which can lead to a personal union.

Royal marriage: If two countries have the same dynasty [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 the other country and anyone else with the same dynasty and a royal marriage. If another country has the same Dynasty and claimed throne then a succession war will start.

Claim throne: If you have a royal marriage with another country and they have a disputed succession (either no heir or an heir with low legitimacy) 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. It makes your monarch the favored successor should their king die without an heir; however if another country has also claimed their throne, and have both the same Dynasty as the target, it will result in a succession war. 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.

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[edit]

A personal union can end in two ways, either with the incorporation of the junior partner in the senior partner or with the junior partner declaring their independence and choosing a new monarch from their nobles.

Integration & inheritance[edit]

After 50 years the senior partner can inherit or integrate the junior partner. Inheriting is random; 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 skill of the senior partner and the size of the junior partner. Large countries can never be inherited.

Alternatively, if you have over 190 relations with them you can take the diplomatic action "Integrate" to immediately start the process of integrating them. This will take a certain amount of time depending on the basetax of the nation (one month per basetax), and the diplomat cannot perform any other missions during this time, unless you cancel it. To see the modifiers and how long it will take, hover over the icon in the diplomacy screen or in the outliner once it's started. Either way, it will end with the senior partner owning the junior partner's territory with cores on all their provinces, even the ones the junior partner themselves didn't have cores on. It cost 15 dip power per month

Rebels that change government type or state religion and enforce their demands in the provinces of the junior partner to be integrated may instantly cancel the annexation process and will break the Personal Union.

Only AI controlled nations can be inherited, but even player controlled nations can be incorporated.


If the senior partner's king dies while having negative prestige or negative relations with the junior partner (junior partner dislikes senior partner), the junior partner will declare their independence and choose a new king. The senior partner will get a "Restoration of Union" casus belli to reclaim the throne for 60% warscore. A player can also declare war on their senior partner to gain their independence.

Special cases[edit]

The junior partner of a junior partner has no special relationship with its senior partner's senior partner. It doesn't count against the number of diplomatic relationships the seniors partner senior can have, does not grant and does not get military access, but will be automatically called to arms by its senior's senior.