Question about vassalization

[Iosif Stalin]

So I'm doing a Venice campaign right now and I'm allied with France. For a period of time I was at war with Milan (which was rough because I'm also at war with the Holy Roman Empire, and much of my military is in the east fighting the Byzantines, so I was having to defend my capital with a weak garrison over and over). At one point I sent a diplomat to Milan begging for peace, offering to pay some ridiculous amount of tribute for 10 or 20 years. They decline. Eventually France accepts peace with Milan by becoming Milan's vassal. So I think "bummer, there goes my ally, now Milan gets to throw everything it has at me". Then, a while later, I suddenly notice I'm no longer at war with Milan. I don't get why. They refused all my peace offers. The only thing I can think of is that I'm allied with France and France became Milan's vassal, which must have forced Milan to make peace with me? Is that what happened? The way I figure it, it must be because France's vassalization made France Milan's ally, and Milan couldn't be at war with a third country that its ally is allied with. It seems to me that the vassalization should have broken France's alliance with me, but instead it seems to have forced Milan (the winner) to end its war with me. It's rather odd. Is it supposed to happen that way?

I'm not complaining though, because it meant I got to form a trade agreement with Milan, bringing in some badly needed cash, and it significantly reduced the pressure on me in Italy. At some point though I'm gonna need to go to war with them again, because they're getting way too big and powerful now. But for now the breathing room is really nice.

[♔atthias♔]

So I'm doing a Venice campaign right now and I'm allied with France. For a period of time I was at war with Milan (which was rough because I'm also at war with the Holy Roman Empire, and much of my military is in the east fighting the Byzantines, so I was having to defend my capital with a weak garrison over and over). At one point I sent a diplomat to Milan begging for peace, offering to pay some ridiculous amount of tribute for 10 or 20 years. They decline. Eventually France accepts peace with Milan by becoming Milan's vassal. So I think "bummer, there goes my ally, now Milan gets to throw everything it has at me". Then, a while later, I suddenly notice I'm no longer at war with Milan. I don't get why. They refused all my peace offers. The only thing I can think of is that I'm allied with France and France became Milan's vassal, which must have forced Milan to make peace with me? Is that what happened? The way I figure it, it must be because France's vassalization made France Milan's ally, and Milan couldn't be at war with a third country that its ally is allied with. It seems to me that the vassalization should have broken France's alliance with me, but instead it seems to have forced Milan (the winner) to end its war with me. It's rather odd. Is it supposed to happen that way?

I'm not complaining though, because it meant I got to form a trade agreement with Milan, bringing in some badly needed cash, and it significantly reduced the pressure on me in Italy. At some point though I'm gonna need to go to war with them again, because they're getting way too big and powerful now. But for now the breathing room is really nice.

I bolded the right answer