Siege - When to use Drill promotions?

[Dr.Null]

I usually go straight up the City Raider line on my siege units, with maybe a few Barrage left at home to suicide against unexpected invasion stacks when my main stack is off having a foreign adventure.

Last game I tried using Drill on some cannons just to see if I could feel any benefit, but the only impression I got was that they died just as fast as CR cannons in the open, and they died way more often when attacking a city.

So, what's the use for Drill promoted siege units?

 

[Bezurn]

Depending on the odds they are facing in open field attacks I think it is to give them a slight edge in surviving an offensive attack. Of course Combat raider is the most popular promotion for this type of unit, since that is where combat takes place the most in the game it seems.

I have put it on some defending siege I placed in a fort and it seems the sensible thing to do in that case. The biggest problem with using this tactic though is that (beyond using a fort, I know, right?) is that siege units will only ever receive 1 xp for each combat regardless of the odds, so getting a well promoted Drill siege requires to have a good unit pump with the right civics / great generals, as the best parts of going drill are the 3rd and 4th promotion to get the most impact of the first strikes.

 

[babar]

I believe the main use is to increase the chance of actually damaging a really strong unit at all (like catapult vs a highly promoted longbow). It's a pretty marginal increase though I think, and city raider will do more damage if it gets a hit. Hopefully someone else can explain the numbers involved.

 

[jwez11007]

As I understand it the strength of drill promos has little to do with increasing combat odds and I believe the game doesn't always take them properly into account. Drill promos are great for minimizing damage. While they slightly improve combat odds, their lack of actual str modifiers leads to their minimal effect on combat odds. The biggest difference between drill and non-drill units is how much HP those that survive have (drillIV units will usually win favorable battle consistently maintaining full health. This is because drill units have the same odds of winning each combat round as the base unit, they just get a couple of free rounds in at the start.

Think of it this way if an archer gets a couple of free shots (first strikes) at a tank it's unlikely to hit it in any of the combat rounds, even it's first 'free' rounds. In this case the archer will gain no advantage promoting up the drill line. However if the archer promoted up something like combat or CG and was defending, it would gain slightly better odds of winning each combat round than the base unit and the drill unit b/c C and CG modify base str of attackers and defenders. If however you find yourself with a couple rifles facing a stack of muskets in the open field, drill looks a lot nicer. As long as your units have decently favorable odds (probably noticeable over 60% becomes increasingly noticeable at better odds), promoting up the drill line will allow them to attack and win the battle while taking less damage. This is because all of a sudden those bonus 'free punches' at the beggining have a high probability of hitting the unpromoted muskets so your rifles have to win fewer 'standard' combat rounds each of which puts them in danger of picking up some damage. It's not uncommon for some drill IV units with odds in the 80-90s to win combat without taking any damage

Long story short, use barrage until combat odds favor you then switch to using drill if you want to bomb the stack to minimum (usually unneccessary but an option none the less).

 

[babar]

Long story short, use barrage until combat odds favor you then switch to using drill if you want to bomb the stack to minimum (usually unneccessary but an option none the less).

My problem with this is that you are wasting a chance to use the experience for more useful promos. Your CR or barrage siege are taking all the attrition at low odds, so you will be left mainly with a bunch of comparatively useless (although healthy) drill siege units.

I tried writing an explanation of when drill might be more likely to cause some damage when massively outclassed, but had to give up because I don't know the maths. I have read it somewhere on these forums though, so hopefully someone will enlighten us.

 

[WelshGandalf]

I have a Drill IV cannon as part of a stack, it wins most battles with 75-80% chance of victory without taking any damage. I have some city raider cannons with it too but they usually take some damage whereas the Drill IV cannon doesn't need to pause to recover. The odds of victory stated were actually quite similar to CR2 cannons as far as I can remember.

It's also good for open-field combat as earlier suggested.

I used to be all CR siege units but after seeing this Drill IV cannon in action I think I'll try & mix up by stacks a bit.

 

[Bezurn]

What some people may not take into account is the fact that unlike any other combat unit in the game (besides aircraft) a siege unit cannot destroy another unit. Therefore, the quicker it can get in the hits to cause the max amount of collateral damage the quicker it can withdraw from combat before it is destroyed.

 

[babar]

So the idea is that an attacking drill siege unit comes to the conclusion of its battle quicker than an ordinary drill unit, because it will withdraw once it achieves maximum collateral damage? I have never heard this before. I always thought a siege unit's withdrawal was dependent solely on its battle with the defending unit. Also I was under the impression that siege causes the same collateral damage regardless of how many times it hits the defending unit.

 

[Farm Boy]

You have it right babar. Siege withdraws when it "wins." If the siege weapon lands what would otherwise be a killing blow to the defending unit, the cannon(or whatever) withdraws from combat. Its collateral is unaffected by its combat with the defending unit.

Drill is not great for siege assuming you don't have a stupid large tech advantage. CR attacking into cities is almost always better. Barrage when defensively counterattacking is likely a better option.

I will however, sometimes promote a couple cannon down the drill line as I am marching an offensive stack through enemy territory. Since there are not a terribly large amount of things you can do to avoid AI "harassing" attacks when they have everything roaded post-engineering and your stack moves at 1 tile per turn, you are probably going to catch some attacks that cause collateral damage. That is not unlikely to force your siege into the unfortunate role of defending(since they did not eat the collateral). In this situation, drill promotions are just about the only thing that improves their ability to be awkward stack defenders at all.

It has been noted siege gains exp slowly and it likely to die on defense. Drill 1 and 2 are not great promotions, so this "tactic" if it can be called that is best when you have a city that can crank out the siege with most of the exp built in. "Hello Spain, how are you?"

This situation is also more likely to arise if you pursue a strategy of say, beelining steel and going to war with built/upgraded cannons and drafted muskets. Unless you are on a defensive tile when the harassing attack comes, the cannons are going to defend by default.

 

[snepp]

I tried writing an explanation of when drill might be more likely to cause some damage when massively outclassed, but had to give up because I don't know the maths. I have read it somewhere on these forums though, so hopefully someone will enlighten us.

Check the combat mechanics article in the War Academy. Not only is the article itself excellent, but it links to a thread that probably contains 4 years worth of posts.

 

[babar]

Check the combat mechanics article in the War Academy. Not only is the article itself excellent, but it links to a thread that probably contains 4 years worth of posts.

Thanks. I had a look but I'm fairly maths illiterate, so I can't figure anything out myself, and didn't find anything specifically answering the question at hand. I do have general understanding though I think.

Taking the example of a two promo catapult vs a CGIII, drill IV longbow.

By reducing the number of longbow free strikes, drill increases the chance that the catapult will survive into normal combat, where it can actually score a hit.

City raider on the other hand increases the likelihood of winning a given round, and not losing a given round during the longbow's first strikes.

But what does this add up to? (besides two dead catapults). I can't figure out which is more likely to score a hit. My guess is that reducing the longbow's first strikes is more significant than slightly reducing the massive strength disparity.

(City raider also increases the damage done if the catapult hits, and reduces the damage when the longbow hits, but this is obviously irrelevant for the purpose of this question.)

 

[VoiceOfUnreason]

Taking the example of a two promo catapult vs a CGIII, drill IV longbow.

Let's stick that longbow (100hp) in a city, and fortify him as well.
That gives him 125% in bonuses (CG3: 75%, City:25%, Fortify:25%) for a strength of 13.5. He also has 4-7 first strikes

For a baseline, we use an unpromoted catapult, so strength 5.

So in each combat round, if the longbow wins (72.973%), he deals 31hp of damage. If the catapult wins, we deal 12hp of damage.

Crunching lots of numbers, the change of doing some damage to the longbow is about 12.36% ~ roughly one in eight. That seems about right, given my world builder tests, so I think I've got the calculation right.


If the catapult is promoted with Drill II, then the catapult has 1-2 first strikes. Our first strikes cancel out some of his, so he'll have 2-6 first strikes (no longer evenly distributed). Net result: a 28.08% chance of doing some damage.

With City Raider II instead, you cut down the strength of the longbow by 45% to 10.8. In each combat round, the longbow wins 68.354%, dealing 28hp damage; the catapult delivers 13hp of damage. Net result: a 17.92% chance of doing some damage.


If we add walls to the city, we buff the Longbow by another 50%. The new chances of doing some damage are

No promotions: 2.34%
Drill II: 9.95%
CRII : 11.90%

Yeah, the walls changed which promotion is "better". Here's the dope: when the ratio of the strengths is about 3.15, the amount of damage per hit goes from 33hp to 34hp. Which means that the number of rounds required to kill drops from 4 to 3.

In this case, the CR promotions take us from a ratio of 3.3 to a ratio of 2.76, crossing the jump point. The CRII catapult can survive one more hit, which for the purposes of this exercise is essentially the same as giving it a first strike (in addition to the extra damage and extra probability to hit).


That 3.15 ratio roughly translates to 162% defensive bonus. So if the longbow is below 162%, Drill II offers the better chance to do some damage. If the longbow is above 207%, Drill II is probably the right answer again. Between those numbers, the two CR promotions will cross the jump point, and probably give the better result.

 

[babar]

Thanks for clearing that up VoiceOfUnreason. That is interesting about the jump point. Besides that, it seems like drill may actually be worthwhile for a properly suicidal, doomed siege unit (provided the target doesn't ignore first strikes).

 

[snepp]

That's some good stuff there. I'll have to take a closer look at my siege the next time I'm throwing a lame duck at a city.

 

[Dr.Null]

Very nice, thank you.

Now how about the case where the siege unit starts off with 3 or 4 promotions (which is not that hard for a Charismatic leader).

For 3 promotions, how does Drill 3 compare to CR 3? The 2 first strike chances ought to help even the odds against Drill longbows, but the benefit of CR 3 is pretty big compared to CR 2. Is there a "tipping point" here, or is CR 3 simply better than Drill 3?

For 4 promotions, how does Drill 4 stack up against... CR 3 + Drill 1, I guess?

 

[babar]

Very nice, thank you.

Now how about the case where the siege unit starts off with 3 or 4 promotions (which is not that hard for a Charismatic leader).

For 3 promotions, how does Drill 3 compare to CR 3? The 2 first strike chances ought to help even the odds against Drill longbows, but the benefit of CR 3 is pretty big compared to CR 2. Is there a "tipping point" here, or is CR 3 simply better than Drill 3?

For 4 promotions, how does Drill 4 stack up against... CR 3 + Drill 1, I guess?

Without asking VoiceOfUnreason to do any more number crunching - I think it really is quite complicated, and the variations are endless (what about different longbows, terrain, fortification, or different units entirely etc), the simple answer might be that if CR III doesn't bring the defender's damage inflicted to below 25 (in this case it doesn't), drill III is probably better.

 

[obsolete]

but the only impression I got was that they died just as fast as CR cannons in the open

No they do not. I believe your sample size must have been too small.

I use Drill siege all the time (Machine guns, haha!). But yes, also on other seige. I've also seen a lot of the top players do this as well when on defense or other odd open-ground situations, so it has a benefit when things are just right (or bad).

 

[Dr.Null]

Without asking VoiceOfUnreason to do any more number crunching - I think it really is quite complicated, and the variations are endless (what about different longbows, terrain, fortification, or different units entirely etc), the simple answer might be that if CR III doesn't bring the defender's damage inflicted to below 25 (in this case it doesn't), drill III is probably better.

Ah, so if you can reduce your death threshold from 4 hits to 5 hits, then you're doing better than getting 2 first strike chances. Is that your thinking here?

If so, it seems like Drill 4 would be superb.

No they do not. I believe your sample size must have been too small.

I use Drill siege all the time (Machine guns, haha!). But yes, also on other seige. I've also seen a lot of the top players do this as well when on defense or other odd open-ground situations, so it has a benefit when things are just right (or bad).

Well, I was talking about attacking stacks in the open, as the idea of using Drill siege to defend didn't occur to me (except Machine Guns, of course).

Maybe it's just that Drill 1 & 2 suck compared to Drill 3 & 4, so the effect was too small to notice at my sample size.

 

[VoiceOfUnreason]

Maybe it's just that Drill 1 & 2 suck compared to Drill 3 & 4, so the effect was too small to notice at my sample size.

Drill II and Drill III are essentially equivalent. Drill III gives 0 first strikes as often as it gives 2, and Drill II costs less. I don't have an opinion on whether that's OK, or it sucks; clearly they are both the same.

Drill I? That sucks.

 

[Iranon]

How important is it whether the top defender is wounded or not? From my experience, Drill becomes much more powerful against wounded units but I'm not sure whether this always applies or just when one actually gains first strikes instead of eliminating those of the wounded defender.