Taking a few provinces causes most of Europe to attack me.

[Iridius]

I took some Dutch provinces as Flanders and it caused a coalition from Hibernia to the Black sea to stomp me with half a million soldiers.

Any tips?

[grotaclas]

The number of provinces which you take don't matter. What matters is the amount of development and the other values which go into the AE formula[eu4.paradoxwikis.com]. If countries from the black sea joined a coalition, you probably had a lot of AE already(e.g. from previous wars or because you broke a truce or attacked without a CB)

[Iridius]

Originally posted by grotaclas:

The number of provinces which you take don't matter. What matters is the amount of development and the other values which go into the AE formula[eu4.paradoxwikis.com]. If countries from the black sea joined a coalition, you probably had a lot of AE already(e.g. from previous wars or because you broke a truce or attacked without a CB)

I had a CB, it's weird. Am I not allowed to take more counties than what the CB permits?

[bri]

Taking land in the HRE is a dangerous thing and requires proper planning. When making peace keep an eye on the bottom right border of the peace screen. A crossed flag icon appearing means that your current proposal would generate enough aggressive expansion diplomacy penalty to push one or more nations past the -50 limit and make them eligible to form/join a coalition against you. Hovering the mouse over the icon will pop up a list of such nations so youi can see what you might be getting into before you actually send the peace deal.

Having a CB just gives you an excuse for war and possibly some war score cost adjustments, AE reduction (note not elimination), and prestige effects. Taking stuff is still going to generate some ae even for the claimed province(s).

[Iridius]

Originally posted by bri:

Taking land in the HRE is a dangerous thing and requires proper planning. When making peace keep an eye on the bottom right border of the peace screen. A crossed flag icon appearing means that your current proposal would generate enough aggressive expansion diplomacy penalty to push one or more nations past the -50 limit and make them eligible to form/join a coalition against you. Hovering the mouse over the icon will pop up a list of such nations so youi can see what you might be getting into before you actually send the peace deal.

Thanks for the advice. I will adjust accordingly.

[grotaclas]

Originally posted by Iridius:

I had a CB, it's weird. Am I not allowed to take more counties than what the CB permits?

Having a CB is not the same as actually using it. If you lost stability or got war exhaustion from the war declaration, you probably also got AE from the war declaration.

If you take provinces or other peace terms which are not covered by the CB, you have to pay dip points for "unjustified demands" and you don't get any discounts to AE or warscore cost which the CB offers. But the typically used conquest CB doesn't offer any AE reductions anyway and the only warscore cost reduction which it gives is for the one province which you selected as the wargoal(you have to occupy that province to get the warscore cost reduction).

[Marquoz]

The best way to expand within the HRE is to force vassalization on your enemy. This generates less AE and also prevents the Emperor from demanding unlawful territory from you. Of course, you then have to integrate your new vassal, which you can't do for at least ten years, but that's ok. They'll fight for you and provide income and force limit increases in the meantime.

Iridius, if you're new to the game's mechanics, I really don't recommending playing a weak starting nation like Flanders. You should explore EU4 with a strong and simple country like the Ottomans instead.

[Totally Innocent Chatbot]

The main issue is that the Low Countries region has some of the most densely concentrated development of any region in the entire in-game world. Combine that with the fact that most of those provinces are in the same culture group as nearly the entire rest of the HRE, are also of the same religion as the rest of the HRE (at least until the Reformation starts spreading everywhere), and the +50% modifier to Aggressive Expansion from the provinces being part of the HRE in the first place, and you're looking at the perfect recipe for massive coalitions if you expand too fast. Unless you find an opportunity to use a Reconquest CB in that region, you're unlikely to be able to take more than one or two provinces per war without having serious issues with AE.

You can see ahead of time a fully detailed breakdown of how much Aggressive Expansion a peace deal will generate before pushing the button to finalize that peace deal. If enough AE will be generated to make any other nations willing to join a coalition against you, a symbol of crossed flags with a sword through the middle will appear at the bottom-right of the menu where you negotiate the terms of peace. Hovering your mouse over that symbol will inform you exactly which nations would be willing to enter a coalition against you if you ended the war with the currently selected demands. A screenshot of this from the wiki is linked below.
https://eu4.paradoxwikis.com/File:Eu4demandtribute.jpg

This will allow you to see at a glance if what you were planning on taking would trigger a continent-spanning coalition, so you can adjust your demands accordingly. Unfortunately, the Low Countries aren't going to be getting any less rich over time, so the only real way to deal with it is to just keep chipping away at them somewhat slowly and letting your Aggressive Expansion tick back down over time.

[Huey]

Taking land from secondary opponents generates more aggressive expansion than taking land from the the enemy war leader, doesn't it?

[bri]

Originally posted by Huey:

Taking land from secondary opponents generates more aggressive expansion than taking land from the the enemy war leader, doesn't it?

It depends. If you make a separate peace then most likely. If they aren't a co-belligerent then most likely but it depends on the actual circumstances involved.

[Iridius]

Originally posted by Totally Innocent Chatbot:

The main issue is that the Low Countries region has some of the most densely concentrated development of any region in the entire in-game world. Combine that with the fact that most of those provinces are in the same culture group as nearly the entire rest of the HRE, are also of the same religion as the rest of the HRE (at least until the Reformation starts spreading everywhere), and the +50% modifier to Aggressive Expansion from the provinces being part of the HRE in the first place, and you're looking at the perfect recipe for massive coalitions if you expand too fast. Unless you find an opportunity to use a Reconquest CB in that region, you're unlikely to be able to take more than one or two provinces per war without having serious issues with AE.

You can see ahead of time a fully detailed breakdown of how much Aggressive Expansion a peace deal will generate before pushing the button to finalize that peace deal. If enough AE will be generated to make any other nations willing to join a coalition against you, a symbol of crossed flags with a sword through the middle will appear at the bottom-right of the menu where you negotiate the terms of peace. Hovering your mouse over that symbol will inform you exactly which nations would be willing to enter a coalition against you if you ended the war with the currently selected demands. A screenshot of this from the wiki is linked below.
https://eu4.paradoxwikis.com/File:Eu4demandtribute.jpg

This will allow you to see at a glance if what you were planning on taking would trigger a continent-spanning coalition, so you can adjust your demands accordingly. Unfortunately, the Low Countries aren't going to be getting any less rich over time, so the only real way to deal with it is to just keep chipping away at them somewhat slowly and letting your Aggressive Expansion tick back down over time.

Thank you for this super detailed response. The people on this forum are great.

[Hunkthebear]

Another thing that i have not seen mentioned is that the Coalition Map mode displays the Aggressive Expansion to nations that have it, so using it is a great way to tell at a glance who is mad at you for taking territory. A solution to Aggressive expansion is using diplomats to raise opinion of countries that you have no current interest in attacking and finding ways to raise your Diplomatic Reputation (National Ideas, Idea groups, Advisors. etc.) as this will increase the amount that Aggressive expansion ticks away.

In general, Playing in the HRE is slow and complicated compared to most other nations due to the increase amount of allies countries have, the extra +50% AE Penalty, increase core costs, and the risk that the current Emperor kicks your teeth in Imperial Intervention Wars.

[Medicles]

Originally posted by Hunkthebear:

Another thing that i have not seen mentioned is that the Coalition Map mode displays the Aggressive Expansion to nations that have it, so using it is a great way to tell at a glance who is mad at you for taking territory. A solution to Aggressive expansion is using diplomats to raise opinion of countries that you have no current interest in attacking and finding ways to raise your Diplomatic Reputation (National Ideas, Idea groups, Advisors. etc.) as this will increase the amount that Aggressive expansion ticks away.

In general, Playing in the HRE is slow and complicated compared to most other nations due to the increase amount of allies countries have, the extra +50% AE Penalty, increase core costs, and the risk that the current Emperor kicks your teeth in Imperial Intervention Wars.

Its not Diplomatic Reputation, but the Improved Relations modifier that increases the amount of AE that decreases each year.