A crusade can only be called if there is no current crusade target. A target remains so for 20 years or until it no longer exists. Being at War with the Crusade target gives the Crusader modifier which gives.
- Gain +30% Manpower.
- Gain +10% Taxes.
- Gain 0.1 Morale of armies.
- Gain +1% Prestige yearly.
- Gain +5% Papal Influence yearly.
Excommunication can only be directed at a ruler whose relations with the Papal State are below 100 and is not the Defender of the Catholic Faith. For Personal Unions, only the senior partner's relations are taken into account although the excommunication penalty effects all junior partners as well. The final restrictions for excommunication is that the year 1650 has not been reached and that no other ruler has been excommunicated in the past 3 years.
Excommunication allows other Catholic nations to wage war on the excommunicated ruler with the Excommunicated Ruler CB. This provides a 25% infamy and 50% cost modifier on almost all demands, most importantly annexation and province cessions.
Clearly this can be highly advantageous to a Catholic nation wishing to assimilate a large portion of Western Europe. However, there are a number of guidelines to follow for this to work.
- Having a high papal influence increases the chance a cardinal will come from one of your provinces. Therefore it is highly advantageous to maintain a high Papal Influence.
- The National Ideas Church Attendance Duty, Divine Supremacy and Unam Sanctum provide an additional 5% annual influence.
- Contrarily the Humanist Tolerance and Ecumenism National ideas provide annual penalties to influence. These NIs are to be avoided.
- Relations with the Papal State provide from -10% at -200 relations to +10% at 200 relations annual influence.
- Controlling the Curia also provides a 5% annual influence gain helping to preserve control once it is gained.
- Infamy reduces influence by a rate of 1% per year per infamy. While the benefit of increasing the number of controlled Catholic provinces helps offset the influence penalty as far as gaining cardinals is concerned, it is still best to be mindful of infamy.
If expansion proceeds uninhibited, the nation eventually holds so many Catholic provinces that its ruler tends to always hold Curia control. While any Catholic nation could attempt to expand via this strategy there are a few nations which are in a superior position.
- England - Powerful navy, large nation, narrowminded. The large navy allows for expansion to distant Catholic nations more easily. Geographical isolation helps keep any conflict on England's terms.
- Castille - Similar to England but less geographically isolated.
- Bohemia - The added support of being Holy Roman Emperor allows Bohemia multiple methods to expand.