This mission is extremely tough, you have to capture the entire country without losing your generals. To start off I recommend going west, slowly push west and take the town there to unlock a new reinforcement army that can help you. At this point the enemy will send their all at you from the south so just simply hold and defend until their force is mostly defeated. Swing south and take London which will unlock another reinforcement force to the south west. Use them to take the nearby town which should be minimally defended if you took out the enemy assault earlier.
Once all the eastern and southern parts of the country are taken, you can head across the mountains west for the last objective. This one could be tricky because the enemy reinforcement generals spawn here. If you did what I did, most of the country should be completely empty which will lead the enemy generals to run off and try to fight some of your troops, take advantage of this and siege down the final town.
Once all the towns are taken you win! Congratulations on beating every single Angevin Dynasty Campaign!! This one was by far the most difficult for me but I really hope this video helped you somewhat, good luck everyone!!
