Joan of Arc 3: The Cleansing of the Loire
Note that you are restricted to the Castle Age in this scenario. To win, you will need to assault several castles. These two facts already define to a large extent how the scenario must play out. The only realistic way to attack castles in the Castle Age is with battering rams, and experience tells us that 5 is the optimum number. Less than that, and the attack might fail, but you don't want them to take up too many spots in the population roster. Furthermore, if you plan to recruit over the population limit, then you can't afford to lose any rams, which means that you have to defeat the enemy's mobile force, at least locally, before attacking a castle.
Move the scout towards the flag. You will acquire some Transport Ships. Use them to cross the Loire River, and then move your units to the east, as per the scenario instructions. At the edge of the map, you find some gold and stone, and if you do it properly, 14 sheep. Trees are everywhere, of course. Set up your base there. At this point, you will have explored about 20% of the map.
Take out the two Burgundian Towers in your base area. This can be done without sustaining any damage by dodging the Tower arrows, but if you use only infantry, then any damage can be healed, even before you get monks. Your base area has four natural entry points. Seal them with a gate each immediately, and add a Tower each as soon as you can. You should be safe behind stone walls well before the first attack arrives.
Keep scouting. You should be able to explore the entire map, with the exception of the vicinity of the main British base, the three British fortified outposts, John Fastolf's territory in the NE corner, and the Burgundian base.
You will have noticed that the British have warships wandering around, so your next priority should probably be a fleet. This is primarily a land map, so you don't really want more than 5 War Galleys. Use your fleet to defend your dock area.
As soon as you have monks and cavalry archers available, start raiding Burgundy.
There is a British dock on the Loire River. Destroy this dock as soon as practicable. The British do not rebuild this dock, not that they really could if they wanted to. They do replace it with another dock further inland. After that, their new production warships come wandering down the tributary one by one, and if they get by your main base, what's left of them gets chopped by your fleet. Destroying the British dock on the Loire River gives you complete control of the Loire River. This allows you to fish and transport troops on the river in complete safety.
Take out Burgundy
You don't have to do this to win the scenario, but if the fact that they are weak is not sufficient reason, then consider the fact that they are consuming resources that would be better used for the glory of France. In particular, they have a large number of gold mines that they will absorb, which you could be utilizing. Burgundy doesn't have much in the way of defenses, only some Towers and some troops. A handful of heavy cavalry and a handful of cavalry archers is all you will need to defeat Burgundy. Of course, you will need to run back to your base for healing from time to time. This is one reason why it is so important to have free rein on the Loire.
While you're heavily engaged with Burgundy, you should build a fortified position, including a castle, on the left side of the map. For one thing, there are important resources over there that you should exploit. For another, having a base over there will allow you to operate more effectively, and its influence actually is felt over the entire map.
After Burgundy is out of the picture, you have to decide what to do about Fastolf's army. If you mostly avoid them, they may not bother you too much, and if they do attack you, they will always be biting on stone. Fastolf's army uses heavy cavalry and maybe some siege equipment, but no heavy artillery. They can't really hurt you. The only question is whether they can interfere with your attacks on the British bases.
For the sake of argument, let's say you decide to take out Fastolf before the bases. It turns out that this is actually very hard. For one thing, his heavy cavalry is better than yours. What can you do about this? Say it: M - O - N - K. That stands for raid - retreat - possess - heal. Repeat as many times as necessary. Eventually, and that means after a long, long time, and having defeated hordes and hordes of enemy units, literally as many as a thousand, considering all enemies, Fastolf runs out of gold, and then you can crush him.
With Fastolf out of the picture, you can take your force of battering rams that has been waiting patiently for the chance against one British castle at a time. Make sure that you have a lot of supporting units, because you don't want to lose any rams, and the British are probably still producing units. Of course, if you can wreck their economy, you should probably do so. Each of the British fortified outposts produces one type of unit in addition to Longbowmen. One produces cavalry, one produces infantry, and one produces siege weapons. The main base produces several types of units. Take this into account in your attack plan.
Attacking the British castles
The British castles themselves are well-designed with two Guard Towers with upgraded range out front, complete Fortified Walls under overwatch range of the castle, and sally forces. Without heavy artillery there is no cheap way of taking these down.
The best way to attack one of the British castles is to build a small wall compartment onto the outside of the British wall. Then move your assault group into the compartment. This protects them from counterattack. Then breach the enemy wall and rush the castle.
After you destroy the first British castle, John Fastolf himself teleports in with a squad of Cavaliers and attacks your base (notably not your forward troops who took down the castle). One castle with Murder Holes will easily defeat this, although you can also use monks to convert the Cavaliers for your own use. Note: If you are playing Age of Kings: Conquerors or later updates, you cannot convert Fastolf to your side due to his Hero tag, and must kill him.
The scenario ends after you destroy three of the castles, so you can't attack all four and don't need to attack Fastolf's base territory.