I was able to capture two cities of The English at Turn.10. If only he had turned a territory next to his existing cities into the new city after both of his cities were captured it would be possible to reach victory at Turn.12. I wish I knew how AI decides which territory to turn into a new city in case all cities are conquered during wars.

I'll attempt to pursue a Turn.11 Victory if I have time to play tomorrow before submissions are closed. I believe it's possible.

Save File:

Turn 015 - Franks - Victory by Vassalizing.ctr