As King of Navarra, I owned just over half of Hispania. Asturias controls most of the other half. It's the year 957. With Ironman mode on, I conquered the Byzantine Empire.
My plan was to press my claim on the Byzantine Empire by attacking Sicily. Many of the holdings there were half empty and it would let me beat whatever BE army came by to stop me because the only ways in were through a straight or through a coastal landing.
It was going well enough with Byzantium spawning a few 1-2k armies, but they were quickly beaten by my 9k (includes 4k mercs) and 5k armies. I was allied to Asturias and they sent some 5k troops over....except they marched them to Constantinople where they were quickly beaten by a 9k Byzantine army. I sent over my 9k army via boat to help but by the time they got there, Asturias was wiped out. The Byz army had ~7.5k men left. At that point, I chased them with my 9k army hoping the Byz didn't stop on mountains/hills/behind a river/all of the above. That's not what happened though.
As it turned out, they were marching all the way to Sicily where my 5k army was still capturing holdings. I noticed and sent them to fight at the straight between Greece and Italy, but the Byz got over it first so I made do with meeting them at a hilly location in southern Italy. My 9k army was close behind and together, they stomped the Byzantine Army and from there on it was smooth sailing till I hit 100%
Now, Constantinople is my capital, most of my Byzantine vassals are Catholic, county conversion is going rather quickly, some of the Catholic lords of Italy have accepted vassalisation (as has Croatia), and some of the Greek children are being raised as Glorious Master Race Basques. The only problem so far is that Byzantine crown authority is at its absolute minimum and I'm having trouble raising it, that and my no. 1 heir (my half-brother) banged his niece so I'm instead giving the crown to my son who has pretty good stats and the Genius trait. (A whole bunch of my family members have positive genetic traits which is pretty cool.) Something I noticed in the new patch is that people are much more willing to seduce family members than they used to be. No me gusta.