May be formed by: Bohemia, Slovakia
- Not at war
- Owns Prague (province id# 625)
- Either Bohemia exists and in your sphere or all Bohemian cores are owned (or their owner is in your sphere).
- Either Slovakia exists and in your sphere or all Bohemian cores are owned (or their owner is in your sphere).
Effect of Formation:
- +10 Prestige
- Czechoslovakian cores added to all provinces with Bohemian or Slovakian cores
- Czech and Slovak added as accepted cultures (if not already primary)
- Capital is moved to Prague
- If Bohemia or Slovakia exists and is either sphered or their sphere owner is also yours then they will be annexed.
- Czechoslovakia has union-ending decisions that may be used if the other half of the union is lost. So, if all Slovakian cores are lost (through war or rebellion) then the union will revert to Bohemia.
- Czechoslovakia is also likely to be released as a whole after a Great War. If a country owns both Bohemia and Slovakia is dismantled after a defeat, Czechoslovakia will be released instead of Bohemia and/or Slovakia seperately.