Siege!
You decide that the power of invention granted to man by God is what you will need to enter this fortress. Siege weapons take time to create but could minimize losses on the battle field. The forest people do not seem interested in leading raids outside of the walls of the fortress which should give you all the time necessary to construct such weapons. There are several siege strategies that your advisors have suggested to you, each requiring a different size force and amount of time to complete. Your options are:
Ranged Siege: You may produce trebuchets of great range and pound the walls of the fortress from a distance. Once a wall is knocked down then your armies may storm the fortress and take it by force. This method should minimize casualties because before the main strength of the army is deployed the playing field shall be leveled and the forest people's defensive strategy shall be lost.
Knock down the gates: You may build two heavily fortified battering rams with iron heads, one as a back up replacement and attempt to knock down the gate of the fortress. Iron plates would protect the men moving the ram from arrows and also protect the wood underneath from fire. Once the gate is battered down men could charge in and take the fortress.
Siege Towers: Siege towers can be constructed, acting as portable towers giving easy access to the walls. This would require the largest force to accomplish but all walls of the fortress could be charged simultaneously overwhelming enemy forces. This strategy would have much loss of life but has a very high likelihood of putting men onto the fortress walls.
The strategy is yours to decide; how best can you crush the infidels and return this temple to its rightful owner, the Church?
Ranged Siege: You may produce trebuchets of great range and pound the walls of the fortress from a distance. Once a wall is knocked down then your armies may storm the fortress and take it by force. This method should minimize casualties because before the main strength of the army is deployed the playing field shall be leveled and the forest people's defensive strategy shall be lost.
Knock down the gates: You may build two heavily fortified battering rams with iron heads, one as a back up replacement and attempt to knock down the gate of the fortress. Iron plates would protect the men moving the ram from arrows and also protect the wood underneath from fire. Once the gate is battered down men could charge in and take the fortress.
Siege Towers: Siege towers can be constructed, acting as portable towers giving easy access to the walls. This would require the largest force to accomplish but all walls of the fortress could be charged simultaneously overwhelming enemy forces. This strategy would have much loss of life but has a very high likelihood of putting men onto the fortress walls.
The strategy is yours to decide; how best can you crush the infidels and return this temple to its rightful owner, the Church?