Annexation is an action where one country fully incorporates a second country, eliminating it. "Turboannexation" is not a true annexation (it does not completely eliminate a country); it is discussed elsewhere. Inheritance is a form of annexation, but it is discussed on its own page.
Effects of Annexation
The annexing country (the annexer) receives ownership of all provinces owned by the second country (the annexee), as well as all of its military forces. The annexee ceases to exist. As with most means of gaining provinces, annexation causes nationalism in any province gained (except core provinces).
The annexing country does not get any other resource owned by or related to the annexee. The annexee's treasury simply vanishes. Similarly any merchants owned by the annexee disappear, leaving empty slots in centers of trade, and all of its projects are terminated. If the annexee had any vassals, they are freed: the annexer does not get them as vassals.
The annexing country suffers a decline in relations with all countries which share the state religion of the annexee. The relations hit is -50 (needs checked) for the player, but it is reduced for AIs depending on difficulty level. Relations are decreated before the check for giving casus belli (below).
Both force- and diplomatic annexation will give a 2-year casus belli to all of a country's "worst enemies", which is any country with relations of -150 or worse.
Other effects of annexation vary with the type of annexation.
Force annexation (abbreviated FA) is a form of separate peace, only available when a country has achieved 100% warscore in a war, that is, it has gained control of all of an enemy's settlements. (Trading posts do not have to be taken to annex.) Furthermore, only single-city countries may be annexed, except for pagan countries.
The annexing country typically incurs a large badboy hit for annexing. (The cost is 3 badboy, or 6 badboy if the annexed country had the same state religion.) Again, there is an exception for pagan annexees: in this case there is no badboy cost at all (for European countries), and a moderate badboy cost for non-Europeans. Annexing a country that contains, or consists of, core-provinces of yours does not change badboy.
The AI will always force annex if it can.
Force Annexation can be turned on or off in options when starting or loading the game.
Diplomatic annexation (abbreviated DA), or "diploannexation" as players sometimes call it, is a diplomatic action. A country can attempt to diplomatically annex a second country only when all of the following conditions hold:
- The annexee is a vassal of the annexer, and has been for at least 10 years.
- The countries are members of the same alliance.
- The countries' state religions are compatible for royal marriage. Note that there cannot actually be a royal marriage between them because of the vassalized state of the the annexee.
- The countries share a land border. This can be anywhere in the world; for example, a trading post next to theirs on a distant continent is sufficient.
- Relations between the countries are at +190 or higher.
- The annexee is not currently at war.
Even when all conditions above hold, diploannexation may or may not work. It rarely fails when there is a huge disproportion in economic and military power, but often fails otherwise. Chances are (or seem to be) increased for the would-be annexer by the following conditions:
- Waiting 30 years to diploannex, not just the minimum 10.
- Having a superior monarch diplomatically.
- Having a superior economy (this seems to be done by monthly income, so, try to annex in a month in which you doing a lot of looting).
- Having a superior military (morale seems to matter, so put your maintenance slider to 100% in the month before you try to annex).
- High stability.
If a diploannexation fails, relations with the vassal will decline by 50 points. Also, there is a chance on each failure that the target country breaks its vassalage.
On success, the target country is annexed as described above. Successful diplomatic annexation costs 1 badboy per province gained (regardless of type, including core provinces and trading posts).