Defending the York City

Description:
My recommended sequence (and tested one) is here:

1. Help the first front line of allies at market section
2. Move to the church at north and activate bells for starting defense of northern part
3. When succesfully defended, get into the castle at east
4. Change the flag at tower and open the gates, this will send allies to try to retake the south
5. When ready, by opening the both south-east gates, you will launch final enemy attack at castle (6)

Tested on vanilla version + hardest difficulty
(Use saves during playing, i got rarely crashed game but dont know what it caused)