City bombardment dmg less than expected

[Gen. Maximus]

I have catapults with accuracry trait and trecbuchets that suppose to gimme a 25% damage on city defence. But I am only getting like 5-10% each time. Am I missing something here? Instead of able to attack the enemy city in the same turn I got to waste one turn to lower the defences 1st. And I do not think the enemy city have castle that help reduces the damage this seems to occur on AI small city.
I am assuming if a city has a +50% defence, it takes two bombardment to reduce it to zero since my damage is 25%. Or is it 25% of 50%, ie 12.5% each time?

 

[Itara]

Walls and Castles reduce the dmg done by non-gunpowder bombardment units (catapuls and trebuchets).

 

[VoiceOfUnreason]

What's really going on is that the city's defenses are being treated much as the strength of a unit is - ie, everything is based on hitpoints, using a 100 point scale.

An unpromoted catapult does 8 points per barrage (CIV4UnitInfos.xml); the accuracy promotion adds another 8(CIV4PromotionInfos.xml). These are the BTS numbers, prior to the siege nerf they were 15 and 10.

Walls [50%] and Castles [25%] (CIV4BuildingInfos.xml) cut into this damage before it is applied to the city.

The effect of this damage is that it reduces the contribution that the city will make to the defense modifier of the units within it. The reduction is linear - an unbombarded city will offer its full defense modifier to its units, a completely bombarded city will offer none, a partially bombarded city will provide a modifier reduced in proportion to the damage done.

In practice, this means that your catapults will appear to be affecting a bigger change to the defense modifier when that modifier is larger.

 

[Gooblah]

I'm going to try to interpret VoiceOfUNreason's explanation to see if I get it-

1) Catapult takes out 8% of defense.
Example 1
City A has 100% defense. No Walls or Castles. Catapult 1 bombards. City A now has 92% defense.

2) A Catapult with the Accuracy promotion does 16% bombard damage.
Example 2
City B has 100% defense, no walls or castles. Catapult 2 has Accuracy promotion, and bombards. City B now has 84% defense.

3) Walls add 50% defense, Castles add 25%
Example 3
City C has 100% defense. It builds walls and castles and now has 175% defense. Catapult 3 has no promotions. It bombards, and City C now has 167% defense.

Example 4
City C has 100% defense. It builds walls and castles and now has 175% defense. Catapult 3 has Accuracy. It bombards, and City C now has 159% defense.

 

[VoiceOfUnreason]

I'm going to try to interpret VoiceOfUNreason's explanation to see if I get it

I don't think you got it.

City A starts with 100 points. An unpromoted catapult reduces that by 8 points with each barrage. So after a single bombardment, the city has 92 points.

City B starts with 100 points. An Accuracy catapult reduces that by (8+8=) 16 points with each barrage. So after a single bombardment, the city has 84 points.

City C, with a wall and a castle, starts with 100 points. An unpromoted catapult reduces that by ( 8 * ( 100 - 75 ) / 100 = ) 2 points with each barrage. So after a single bombardment, the city has 98 points.

Similar math for City D, but the accuracy promotion adds in another 8 points before the reduction by the stonework kicks in, for a net 4 points with each barrage. After a single bombardment, the city has 96 points.


What does 84 points mean? That means that the defenders benefit from 84% of the maximum cultural bonus. In a city that has only expanded to fill the fat cross, that means that the defenders get a 16% bonus instead of a 20% bonus. In the capital, which is already carrying a 80% defensive bonus thanks to all the extra culture, the defenders get a 67% boost.

Does that help?

 

[Gen. Maximus]

It sure looks like walls and castle makes bombardments pin-pricks unless you have a dozen of them! It sure helps me, TQ!

 

[TheDS]

That does explain a great deal!

 

[DMOC]

This makes me want to go to the city raider promotion line instead of the bombarding and accuracy line of promotions.

 

[KrikkitTwo]

Actually All untrue (at least in BTS)

To determine the effect of Bombardment

1. What is the Defense... we'll say 60% (cultural)
and a Catapult takes 8% off of it
so
60->52->44->36-> etc. for each Catapult hit

Now if the City has Walls, the Catapult does less damage

2. With Walls Catapults+Trebs do 50% of their normal damage so only 4 points for a Catapult (with Walls and Castle a Catapult only does 2 points)
60->56->52->48-> etc. for each catapult attack with walls
or
100->98->96->94-> etc. for each Catapult Attack with a Castle


***
3. There is something Wierd if you have a city with Walls or Castles and you are using gunpowder units

Imagine 60% culture but with a Castle
so for Non-Gunpowder units, the defense is 100%, for Gunpowder it is 60%
However, Bombardment works on the Defense it sees
so if a Trebuchet (4% bombard with Castles) attacks our city, the Defense %s are
v. Maces: v. Muskets
100 : 60
96: 96 x(60/100)=57
92: 92 x(60/100)=55

so they take it off the maximum value, and the 'lower value' is calculated in.


Remember Defense is EITHER cultural OR wall+castle (whichever is greater)
Gunpowder units ignore the wall+castle defense

 

[iamnleth]

I just tried to bombard a Khmer city with 80% cultural defense (no walls or castles) with 3 catapults and 4 trebuchets... the defense only went down to 59%?! How?

 

[KrikkitTwo]

^ did it Have no walls or castles, or were you using Muskets to negate them?
(oh and are you using BTS)

 

[kazapp]

The really interesting question is why the Civ team found it necessary to make combat calculations so complex and non-intuitive...

 

[iamnleth]

^ did it Have no walls or castles, or were you using Muskets to negate them?
(oh and are you using BTS)

It had no walls or castles, I my attack force consisted of grenadiers, 3 catapults, and 4 trebuchets, while the enemy city was being defended with only longbows. And it IS BTS. I'm stumped.

 

[Zello]

hm...i was wondering what happened to my siege units in BtS. I used to roll 5 or 6 trebs up to a city and reduce the culture to 0 in a few turns, but this time their combined effort would only reduce culture defense by about 12%. It all seems ridiculously complex (and I'm hoping you guys will be able to clear up exactly what is going on with the bombardment numbers), and makes me want to just mass produce CR kamikazes, which to me seems like the opposite to what siege units were intended to be.

 

[KrikkitTwo]

It had no walls or castles, I my attack force consisted of grenadiers, 3 catapults, and 4 trebuchets, while the enemy city was being defended with only longbows. And it IS BTS. I'm stumped.

OK if you were using Grenadiers, you might not Know if it had walls or Castles
(the Grenadier makes them invisible to you)

If they had Walls+Castles it would be like this
3 cats= 24% 8% each right?
4 trebs=64% 16% each right?
Total =88%
Effect of Walls+Castles: 88% -> 22%

so you would take 100%->58%
58% is what you Should have... according to your Catapults and Trebs (and the announcement)

46.4% is what you should have according to your Grenadiers

[hmm... Were any of your siege weapons damaged, I've never heard of that having an effect but maybe it does.]
Checked code it doesn't


The key change in BTS was
The amount of damage a Siege unit does is now "straight".
If your Artillery does 20% damage that means 2 shots to take out a 40% defense, and 4 shots to take out an 80% defense. (before it would be the same # of shots to take out everything)
To accomodate this, the % that siege units do was decreased.

 

[iamnleth]

It was 59%, not 56%. And I can't see how grenadiers would affect this as I don't think I had them selected for the bombardment (I don't see why I would have had them selected).

Also, I don't believe that the AI had walls or castles. The appearance of grenadiers does not make the walls and castles physically invisible, as you can still see them in/surrounding the city. I'm convinced there were none there. And my seige units were completely unharmed, it was the first seige of the war.

I would love to know the answer to this, I was convinced before the war that my seige units would be able to deal with the defensive bonus. Luckily I had CRIII Grenadiers vs. unexperienced longbows, so even with the defense, their chances of winning were high.

 

[iamnleth]

No more ideas?

 

[KrikkitTwo]

Well I'm stumped too, the Minimum damage the Catapults+Trebs should have done would be
22% with castles Reducing a 100 -> 58 [80->46 according to the Grenadiers]
or
44% with Walls reducing an 80 -> 36
or
80%-> 0% if no walls or castles

I'm stumped, unless you have some type of a mod/remember it wrong

The closest thing would be if they DID have walls+castles, and the Announcement said reduce to 58%

 

[iamnleth]

Well I'm stumped too, the Minimum damage the Catapults+Trebs should have done would be
22% with castles Reducing a 100 -> 58 [80->46 according to the Grenadiers]
or
44% with Walls reducing an 80 -> 36
or
80%-> 0% if no walls or castles

I'm stumped, unless you have some type of a mod/remember it wrong

The closest thing would be if they DID have walls+castles, and the Announcement said reduce to 58%

I saved shortly before the war, I'll reload it and see what results.

 

[iamnleth]

Sorry for the double-post again. I've included a screenshot this time around. Two of my catapults had accuracy, which I had forgotten earlier.

• Two accuracy catapults = 32%.
• One catapult with only barrage = 8%.
• Four trebuchets with city raider/barrage = 64%.

A total of 104%.

But it still makes little sense to me. The city has no walls/castle, as I said before, and everything else I said seems to be correct. Also, the Khmer empire doesn't have Chichen Itza, whether or not that makes a difference.

But... it appears that gunpowder units have an effect anyway, as the city's cultural defense is less with the grenadiers selected. Perhaps this is just something quite normal that I've missed, but if it is, I never knew about it. I thought walls/castle defense were the only thing negated by gunpowder. I've included an image. It's a bit large, to warn you.

Spoiler :

• The first frame is the city pre-bombardment.
• The second frame is the city post-bombardment with the catapults/trebs selected.
• The third frame is the city post-bombardment with the grenadiers selected.

I'm lost, to be honest.