This map is designed as an attacking siege only. Normal or higher is the intended level of challenge.
A few historical notes are provided on the launch page before you begin the siege. For a truly incredible write up of the history of Kenilworth castle. Read Castle of the Week #63 by Angel Sulis. The historical summary he provides is essential to enjoying this siege map IMO.
This map is set at the beginning of the great siege of 1266.
Kenilworth's massive and elaborate water defenses will limit your options of attack and make a direct assault impossible. The Fortress has a productive and abundant food supply. This combined with the castles formidable appearance has given the garrison incredible courage and morale. Accordingly, their 'Troop Combat Bonus' has been significantly boosted. The attacking troop combination should suffice for victory but feel free to alter it, as several different combinations will work.