Longfort is a pretty solid castle, poised along a shoreline. This is a defending siege only, and it will come under Invasions (sorry I dont have an unpatched version installed right now, so I couldnt make a seige with invasions in it). The map should take some troop juggling and movement to defend properly, but it will not be truly fun unless it is edited to a harder level, or the player is welcome to add his own invasions or boost the stregth of them, as the map is unlocked.
Remember your engineers guild, boiling oil is an excellent defence when your goign up against the number of enemies in this scenario
Look at your armory, it should hint something
Defend your food stores, but they are bound to get run over, so use your population while it still stands.
Do you really need all these buildings working? wouldnt extra peasants be a better deal instead?
Have fun, and please Rate; its hard to improve a map without some sort of feedback/
Your map is superbly designed, but the story is mising and there are a few scenario problems. I think you should make buildings unvailable to build, or leave only a few buildings. And I think the Balance would be perfect if there wouldn't be so much weapons in the armory. I will review your map when you will fix the problems.