problem with stronghold 2(not alpha and omega related)

(if tu dont play any of the stronghold games tu wont understand) theres this feature in stronghold 2 called kingmaker where tu try to survive with opposing npcs eyeing you. however, every time i use this feature i start building the walls and it seems as though they have minds of their own and enjoy seeing me suffer. cause every time i go in long before im ready i get full seiges with massive armies stomping out my walls. what should i do to survive this? im sick of seeing the game over screen!!