How to have better siege artillery on the walls when defending

[RubiconDecision]

Although the great scene of Balian defending the walls of Jerusalem didn't happen with flaming ballista and trebuchet, they did have the capability to place their ballistas, catapults, and trebuchet on the walls to defend their settlements. Of course it is extremely frustrating to have built these devices within a settlement, then be attacked, and to use them ineffectually while the attackers send their own diverse projectiles to batter down your walls.

The main reason that you cannot place siege artillery on the walls is a lack of room as well as the way the tooltypes are set for deploying siege artillery on the walls. Other than someone building special thicker walls, and reconfiguring them, there is no way to place your manufactured siege artillery on the walls. Or someone could make platforms with inclines back from the existing walls with IWTE, and then the defenders could deploy their siege artillery on to these special platforms. That's the downside.

You can only place them outside and launch projectiles, but because they are slow, then you have to protect them with infantry and decent long range archers, and so provide cover for them as the attacking army moves forward. That is less than ideal, for it means maneuvering outside the gates with slow moving artillery and potentially losing them.

One could place them further back and so lob projectiles once the enemy gains the wall, and also lob the artillery that can vary the angle enough to get the trajectory over the walls, but it's poorly done. You can also attack the enemy once they get past the walls or even once the attackers break down the walls, there are now openings to fire your own artillery easier.

There is a better way. What you can do is carefully edit the arrow towers specific to the levels of the settlements, and so instead of an arrow tower firing arrows, it now though labeled an arrow tower will send ballista instead. You also can configure certain ballista towers to fire trebuchet boulders instead.

Here is how I did it:

Level 3 Reconfiguring the arrow and ballista towers in descr_walls

{ level 3 siege_tower_size medium wall { full_health 2000 battle_stats flammability_none impact_damage_high localised_name wall } gateway { full_health 1800 battle_stats flammability_none impact_damage_high localised_name gateway medium_wooden medium_reinforced medium_iron } tower { full_health 2200 control_area_radius 30 manned 1 battle_stats flammability_none impact_damage_high localised_name tower ; as in descr_unit.txt level { stat 40, 0, tower_ballista, 150, 10, siege_missile, artillery_mechanical, piercing, arrow_tower, 350, 1 stat_attr no shot_sfx TOWER_BALLISTA_FIRING fire_angle 45 ; unit size reload_ms flaming_reload_ms fire_rate small 8000 9000 fire_rate normal 7500 8500 fire_rate large 7000 8000 fire_rate huge 6500 7500 } level { stat 40, 0, tower_ballista, 150, 10, siege_missile, artillery_mechanical, piercing, ballista_tower, 350, 1 stat_attr no shot_sfx TOWER_BALLISTA_FIRING fire_angle 45 ; unit size reload_ms flaming_reload_ms fire_rate small 8000 9000 fire_rate normal 7500 8500 fire_rate large 7000 8000 fire_rate huge 6500 7500 }

This means the ammunition used in both the arrow and ballista towers are firing ballista projectiles. On lower levels, the arrow towers fire only arrows.

Why not create more levels of the tower? Why not have arrow, crossbow bolt, longbow bodkin arrows, ballista, catapult, trebuchet, musket shot, serpentine, cannon, etc towers? Well I think that you can only have arrow towers, ballista towers, and cannon towers as it is hard coded. If not, then one could create many different kinds of combinations and levels for settlements.

Here is what I did to put trebuchet boulders in Level 4 settlements:

Level 4 trebuchet on the walls

{ level 4 siege_tower_size large wall { full_health 3000 battle_stats flammability_none impact_damage_high localised_name wall } gateway { full_health 2500 battle_stats flammability_none impact_damage_high localised_name gateway huge_wooden huge_reinforced huge_iron } tower { full_health 3500 control_area_radius 30 manned 1 battle_stats flammability_none impact_damage_high localised_name tower ; as in descr_unit.txt level { stat 40, 0, tower_ballista, 150, 10, siege_missile, artillery_mechanical, piercing, arrow_tower, 350, 1 stat_attr no shot_sfx TOWER_ARROW_FIRING fire_angle 90 ; unit size reload_ms flaming_reload_ms fire_rate small 8000 9000 fire_rate normal 7500 8500 fire_rate large 7000 8000 fire_rate huge 6500 7500 } level { stat 40, 0, trebuchet, 290, 10, siege_missile, artillery_mechanical, piercing, ballista_tower, 350, 1 stat_attr no shot_sfx CANNON_FIRING fire_angle 45 ; unit size reload_ms flaming_reload_ms fire_rate small 8000 9000 fire_rate normal 7500 8500 fire_rate large 7000 8000 fire_rate huge 6500 7500 }

On level 4, the arrow towers are shooting ballista while the ballista towers are shooting trebuchet boulders. This seemed more balanced then putting all trebuchet in both kinds of towers.

Now the AI is not smart at all. I set up custom battles and always gave the AI attackers trebuchet. What they should do is keep their army back, lob their ammunition to remove a wall section, then bring up the rest of the army to penetrate those breeches. I intentionally made the attackers stronger than the defenders too to see what would happen.

Instead, the AI attackers placed their attacking army as close to the edge of the deployment line such that they could rush the walls with their siege towers, ladders, and rams. This means they take heavy fire from the flaming ballista and the flaming arrows from my archers deployed on the walls. Naturally though I cannot pick the targets for the new artillery on the walls, the roboarrow towers and roboballista towers intentionally target the siege towers and attacking trebuchet.

What would be best would be if someone would reconfigure the Battle AI for sieging a settlement, taking into account the change in the ammunition of these new arrow towers (that shoot ballista) and the ballista towers (that shoot trebuchet).

It's only a start, but makes defending much more effective and more like history.

Note for attackers, this means that if you do have siege artillery, then you especially want to take out the ballista towers (that actually are shooting trebuchet) and of lesser importance the arrow towers (that are shooting ballista) too. If not, then you will take heavy long range fire and could see your attacking forces annhilated merely because of the towers and rams being burned up too soon.

In my tests of the AI attacking, on level 3 settlements I used archer militia firing flaming arrows to cause the ladder carrying attacking units to rout. On level 4 settlements, I had longbows firing flaming arrows, and since they have a further range, then they could reach the siege towers and burned them up first then attacked the trebuchet. In both cases, the attackers saw at least 30% losses. On level 3, the attackers managed to get to the walls, for the arrow towers that are now firing ballista are SLOWER and hence gives them more time to get more attacking units to the walls, but of course it does more damage. Similarly the ballista towers that fire trebuchet fire SLOWLY, so it makes it difficult as the rams and the siege towers move SLOWLY too, and you can expect to lose quite a few.

It might be worth it to change the descr_campaign_db line:
<no_towers_only_for_city_level string="huge_city"/>
such that ladders can always be used. That way the army attacking a huge city can run their shock troops with ladders which the defending trebuchet are protecting the walls.

Knocking down a wall makes sense, but because the firing rate of the ballista and trebuchet are slow, then one could mix up tactics and run your shock troops up with ladders while lobbing certain wall sections to make a breech and/or taking out that ballista tower (that shoots trebuchet now). Do that well, and you eliminate the defender's ability to use these new artillery towers.

Also note that there is a parameter:
manned 1

What that does is determine if a defending unit is close by, and hence is manning the towers. Of course we know that cavalry being close by can also trigger this so the towers fire.

If one changes that parameter to:
manned 0

then the towers will fire even if the defending units are back at the flagged area.

EDIT: Because on level 4 settlements I added the trebuchet ONLY from the ballista towers, then from an attacker's viewpoint, it makes sense to attack the corners of the walls and not full frontal assault. By doing so, the attacker can avoid the trebuchet as those ballista towers (firing trebuchet ammunition) are solely located on the gate towers. If you look in that picture I attached, you'll see at that location the attackers trebuchet has a better chance of hitting from the hillside due to elevation, and so putting the trebuchet back from the main gates and firing upon it to either breech or knock out the trebuchet towers while simultaeously attacking the corners with siege towers only makes more sense. You still will be taking on ballista fire slowly from the modified arrow towers.

EDIT2: By the way, I've been testing this in Broken Crescent 2.3.2.2 with the JizyaKafirsDimmisV2.0 submod. I sent a powerful Mongol army after the defenders of a Huge City. While the AI initially deploys their army too close, they also relocate them further back and properly attempt to knock down the walls. Ideally the AI could be configured with the Battle AI to attempt to breech a side wall instead of a head on attack, as that would avoid the trebuchet fire. In this case, the roboarchers are set to fire arrows and the cannon towers to fire trebuchet since there isn't gunpowder in that submod.

This results in far fewer losses of huge cities, something which I think would be historically correct.