Territory Defense Question

[Great One]

I have a question about territory defense.

I annexed a small German vassal to use as a seed to take over HRE territory. Knowing that Austria would eventually come knocking, I beefed up the defenses of these two territories. I built up to a level 5 fort in both provinces and built my March special building on the southern province. I also built up the manpower buildings on both provinces. I put a small stack of about 24 troops on the heavy defense territory as a deterrent and to use to conquer nearby popup targets in small German kingdoms. I planned to march over reinforcements in case an all out war broke out.

As luck would have it, my Milan ally (who owned all of Northern Italy so quite a good friend to have) was attacked by Austria. I came to his aid and started marching a stack of 85 troops in to help.

An Austrian stack of 50 troops attacked my defensive territory. The forces there wiped out more than half of his troops, so the defenses were well worth the investment. By the time my stack of 85 came over, they were sieging the province and the stack had recovered to about 35 strong, no problem for my 80 troops...right?

Wrong, I lost 45 troops and received -10 warscore for my troubles. Despite still controlling the strong defensive fortifications in the territory, it did not appear as though I received the bonuses. In fact, if anything, it appeared as though Austria got the defensive bonus despite not actually controlling the fortifications in the territory.

Can anyone explain how this works? Is this a bug, or working as intended?

 

[Xara]

Fortresses don't do anything for the troops except let you sit more of them on the tile without penalty (due to supply limits). Fort upgrades slow the rate of enemy sieging. They don't give you defensive or offensive capability when attacking or defending.

What probably happened was you attacked them while they were in a mountain tile or other heavily-penalized terrain. You got wiped out the same way your defensive group heavily damaged their attacking one before that.

 

[Loha4]

The defensive bonus applies to the amount of time it takes an army to siege a province, I think it worked differently in EU3 but the bonuses don't effect troop battles in EU4. Not to my knowledge anyway.

 

[Xara]

What you should have done, really, is reinforced the first defending group, or retreated them before they got wiped out.
And let them siege the March province with a huge army, it takes years upon years to break a March province and they'll be bleeding manpower the whole time.
Bait the AI into attacking a small force which you can quickly reinforce with nearby stacks. Gives you the defensive benefit. Best done on huge mountain tiles.
Counterattack only when they are severely hurting and can be cleaned up.

 

[Great One]

Thanks for the information. It did take quite awhile for them to siege that province.

One other thing cropped up with this war which seemed unfair.

When I declare war on a country and their allies jump into the fray, I am not allowed to negotiate a separate peace with the target of my wargoal.

In this war, Austria declared on Milan who called me for help in their defensive war. After awhile, Austria got a separate peace with Milan at which point their war goals changed to taking one of my provinces (even though they didn't declare war on me). Because they were holding this province, I was not able to negotiate reasonable terms for peace. Why wasn't the AI restricted from getting a separate peace with the target of their war goal?