Yeah... AI basically gave me Leon tonight.
Declared a holy war to retake it. They'd taken it a few years back with a 20,000 troop stack, mostly from allies.
This time around I not only had Holy Orders to draw upon, but the leader of the Emirate of Leon had just died, leaving the whole shebang to a much less popular youngster. This ended up losing all of their Allies except a few small ones.
It was a tough war, but I started with deep coffers and the Pope chipped in a couple of times because he decided he liked the cut of my jib... or blade...
It took years of dancing around, but because the AI focused almost entirely on Leon, I was able to pop an army back behind their lines and take some of their rear area. I'd hop back up to take the Leon provinces whenever they were all back in enemy hands and to attack any reasonably large but vulnerable armies in my way. Started with an army of 12,000. That got chopped down to about 8,000. I brought a second holy order in. After a while that even got chopped down again. Then a pulled in a few mercenary troops as my troop numbers dwindled. Allies helped a bit, especially a very convenient marriage ceremony to Brittany followed by their dowry of an few thousand troop reinforcement.
Still, I never had a major defeat that entire war, and the AI, had it only stopped focusing on Leon and actually tried to regroup its troops into one stack, probably could have weakened me severely and I would have eventually run out of money. (I started with 800 gold, pope chipped in 400 over the course of the war, and I gained probably between 4 and 500 from dying familyless court members. I ended with about 200 gold.) If it had also tried to retake some of its core provinces I'd probably have never been able to push the war score up to 100% too. I'm happy with the way it turned out, but had the AI been smarter, it wouldn't have turned out that way.
Now, for my next problem... I've got a reasonably old Queen. (56) Whose only heir is a reasonably old half sister (also 56). She also has no living heirs... both have been married since their early 20s, but only the half sister had a single son who died at the age of 2.
Any ideas on how to get some heirs in there? I believe if they both die it passes onto a cousin that's a princess of France of something... but I don't believe they're actually in my dynasty.
It was just bad luck that my previous king had only girls and ended up dying at 80, leaving me in control of a 46 year old childless Queen when he died.