Battle for Middle Earth - Good Campaign - Minas Tirith

Battle for Middle Earth - Good Campaign Map - Minas Tirith (+8 Power)
This is a hint/walkthrough post for Battle for Middle Earth. You can find an index of all our Battle for Middle Earth posts here.

The defence of Minas Tirith presents a lot of problems, not the least of which is your mere 300 Command Point limit.

Initial Army
You start with the army from Osgiliath, which can be as much as 600 or possibly more points after Osgiliath (300 plus calling Faramir as reinforcements). This is trimmed down to 300, and is further reduced by 75 points as this mission starts you off with 5 battalions of level 1 archers with no upgrades.

Preparing Minas Tirith
If you've played the Evil Campaign, you will know that Mordor can summon all the Nazgûl -- and they will, while resources last. You may be tempted to therefore plant a lot of archer towers, but you are going to lose the farms outside, so I recommend instead you place Blacksmiths. These eventually upgrade to level 3 over time, whereupon they receive archer towers anyway.
On the lower level, build some unit producing buildings as you will probably want a short path to the gate or the walls.
Just behind the main gate are two widely-spaced-apart building points, too far apart to overlap. I recommend putting Healing Wells instead of Statues here -- I'll explain why later.
There are four base sites, but none of them are usable by you in this mission.

Overall Strategy
Minas Tirith has a very long perimeter and you do not really have the troops to cover it properly. Instead of a defensive stance and firefighting until you can call Rohirrim reinforcements, I chose to take a strong offence.
If Mordor cannot scale the walls or bomb you behind the walls with catapults, they cannot really do anything to you. Nazgûl can destroy trebuchet towers of course, but even this is useless if Mordor troops arrive at your gates with no siege engines (which can include trolls). So, instead of defending the entire wall perimeter, I aimed to destroy Mordor's siege engines, and also to destroy their resources.
Whenever I could, I scanned Minas Tirith's walls to rebuild any lost trebuchets on Trebuchet towers.

Mordor Wave 1
My forces were reduced to two battalions of Gondor Knights and my full complement of six battalions of Tower Guards-Archers. I grouped the latter with heroes and planted them at the eastern base site and waited for Mordor. The Knights were a little behind these. I sat them all on a patch of Elven Land summoned by the EvenStar power.

Mordor arrived with initially green troops, but quickly followed with strong veteran (about level 7) troops, and then the first wave of (a lot of) catapults. I destroyed as many as these as I could with the Knights, running them around troops which were basically too dangerous to trample since they could survive and hit back. Cavalry are remarkably good at destroying siege engines of all types.
Meanwhile, the Tower Guards-Archers, being right there at the base, quickly destroyed it as Mordor built it. When it looked like Mordor had given up the base, I marched them down to attack the other base that was being built. Shortly after, possibly because Mordor had exhausted its resources, they stopped building the base.
Meanwhile, Mordor troops beelined for the farms and on the way got shot to bits. Only those who had reached the farms sometimes turned back to attack my forces.
The Nazgûl seemed to prefer the farms, but afterwards came after my horsemen. I quickly retreated them to my archers and manually set them to attack the Nazgûl. 30 fire-archers can make short work of a Nazgûl.

Mordor Wave 2
A second wave of Mordor siege engines will look like Siege Towers and Catapults. The Siege Towers can trample infantry, so they had to have priority if they were coming for my troop position. Otherwise, I destroyed whatever I could of the Siege Towers and Catapults and hoped the trebuchets could handle the rest.

Mordor Wave 3
Once you start to see trolls escorting battering rams, that is the start of the end of Mordor's seemingly never-ending stream of forces. Carefully retreat your forces back into the city. Close the gates if you need respite and healing, but otherwise KEEP THEM OPEN to channel the forces inside and destroy them in a crossfire.
If any enemies scaled the walls, ignore them. They will come for your forces, which are ready at the gate and hopefully escorted by heroes with Leadership bonuses (e.g., Gandalf).
Remember that I had suggested Healing Wells at the gates. This allows you to separate your forces into two, so they aren't too bunched up. If enemies come through the gate, they will be caught in the crossfire. Between waves, your troops are healed.
Also, if you keep the gates open, they won't get beaten down by battering rams, so you retain the option of closing them briefly if you suddenly need some respite.
Between waves, ride your Knights out to retake the farms and thereby provide more distractions for the enemy.

Mordor Wave 4
The last wave are Evil Men with Mûmakil and Grond, who sits outside uselessly because you have left the gate open. The Mûmakil did not approach my walls possibly because the trebuchets were still up.
When Mordor finally runs out of forces, Aragorn will come with an army of the dead. Sweep them west to east to clear the field, and you win the mission.