Okay, since yesterday the issues of 1.5.9 are ancient history. 1.5.10 feels and plays vastly differently.
Looks like they tried to hotfix the issue where the ai's small stack attacks lose all progress by tweaking the decision logic whether the ai goes into offense of defense.
How did that work out you ask?
Well... allow me to summarize the state of warfare in 1.5.10 with a little collage of a couple of screenshots that I took while the game was paused:
Summary: The ai now LOVES to sit at the front defending. So much that it often does just that and absolutely nothing else. And no, this is not an isolated incident. It doesn't happen always, but it happens very very often. In my collage, austria was occupied elsewhere. I used that situation to illustrate how absolutely ridiculous the Prussian decision to just sit there for half a year is. But I have also seen France vs Austria both sitting fully mobilized at the front staring at each other, both sides in defensive stance for several years. The attrition casualties went into the millions. Millions of war casualties In a war in the 1840s. Millions of war casualties in a war that didn't even have battles.
And yes, this is of course completely and utterly gamebreaking.
People complain that there is too much negativity on the forum, and rightfully so. I have also been guilty of posting frustrated ramblings that I am not proud of. I do appreciate them trying to hotfix the mess that 1.5 has been so far, I really do. I also appreciate that judging from how they approached the topic, they apparently actually had a rather decent grasp on what the most glaring issues of 1.5.9 were. The problem is of course, that warfare in 1.5.10 is still completely broken, just now in a different way.
All in all, the warfare system still makes this game borderline unplayable, a whopping 14 months after release. Weirdly I am currently still having fun with the game despite that, because the rest of the game is by now in my opinion actually pretty good, once you get the hang of things.