How to defend against battleships and howitzers

Can't beat the AI? Is it too tame? Discuss the best strategies!
clawsoon
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How to defend against battleships and howitzers

Postby clawsoon » Tue Jan 14, 2014 6:31 pm

Note: Editing to include combat calculator results so that hitpoints and firepower (including, from the help files, "If a ship is attacking a land unit on land the firepower of both is set to 1") are taken into account.

It turns out that city-center hills don't help much against howitzers, so howitzers have to be defended against in the usual tactical way, i.e. attack them before they attack you and minimize railroads. Anything I've changed to a tiny font is something I was wrong about in my initial post. (I'm leaving it there so that the ensuing discussion makes sense and readers can see where I went wrong.)

Against battleships, though, the strategy works quite well.


I've seen that some people on the forum are having trouble defending their cities against battleships and howitzers. The secret to holding them off is:

- transform all city centers to hills (after you get explosives).
- put veteran mechanized infantry (labour union) in each city.

Being able to get to labour union before you're attacked by battleships is the hard part, and is an entire topic to itself. You have to master the art of largepox/maximizing the number of ocean squares per city in order to get enough research to get there in time. Getting to gunpowder and democracy early are prerequisites, of course.

However, if you're able to get there, your cities can hold off endless battleship attacks and most howitzer attacks. Here's the math:

Mech. Infantry: 6.0 defense strength
Veteran status modifier: x 1.5 = 9.0
Hills defense modifier: x 2.0 = 18.0
Inside a city defense modifier: x 1.5 = 27.0, which leads to an 82% success rate for a veteran attacking howitzer
Coastal defense modifier: x 2.0 = 54.0, which leads to a 0.06% success rate for a veteran attacking battleship, 1.75% for an elite battleship

Even an elite battleship only has 12.0 x 2.0 = 24.0 attack strength, so you never have to worry about battleship attacks. You should hope for them, actually, because they allow some of your mech. inf. units to gain hardened and elite status.

A veteran howitzer will bring 12.0 x 1.5 = 18.0 against your 27.0 defense, so you'll win most of the time. An elite howitzer gets 12.0 x 2.0 = 24.0, so it's an even match, but if you've got a couple of extra mech. inf. you should be able to pick those ones off after they land and before they attack you.

If you're not able to get to labour union in time, you might have some luck with veteran riflemen (conscription) or veteran alpine troops (tactics) with hills in your city center. Here's how the math works for those:

Rifleman: 4.0 defense
Veteran status modifier: x 1.5 = 6.0
Hills defense modifier: x 2.0 = 12.0
Inside a city defense modifier: x 1.5 = 18.0, which leads to an 99.95% success rate for a veteran attacking howitzer
Coastal defense modifier: x 2.0 = 36.0, which leads to a 51% success rate for a veteran attacking battleship

You'll win most first rounds against battleships, but a flood of battleship attacks could still overwhelm a small number of defender. You've got a 50% chance against a first veteran howitzer attack, but your defenders will be substantially weakened and will probably fall to follow-up attacks unless you've got multiple units per city.

Alpine troops: 5.0 defense
Veteran status modifier: x 1.5 = 7.5
Hills defense modifier: x 2.0 = 15.0
Inside a city defense modifier: x 1.5 = 22.5, which leads to an 99.5% success rate for a veteran attacking howitzer
Coastal defense modifier: x 2.0 = 45.0, which leads to a 22% success rate for a veteran attacking battleship

You'll be mostly safe against battleships, but there's a small chance you'll fall to multiple battleship attacks. You've got a slight edge against veteran howitzer attacks, but multiple howitzer attacks or an elite howitzer attack will again be a problem, so you always have to be prepared to attack howitzers before they attack you.

(As a side note, I usually get miniaturization before labour union, so that my ocean cities have high shield production and can produce lots of their own mechanized infantry once I get labour union.)

Hope that helps someone.
Last edited by clawsoon on Tue Jan 14, 2014 10:52 pm, edited 1 time in total.

clawsoon
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Re: How to defend against battleships and howitzers

Postby clawsoon » Tue Jan 14, 2014 6:43 pm

BTW, if you're not yet at a level where you can manage to accomplish all that before you're attacked, a simple solution is to build your coastal cities on hills. It'll slow down your early research compared to building on plains or grassland, so it's an especially bad idea for your early cities under despotism, but once you've escaped despotism (which should always be your first priority), it's an easy way to double your defense strength while you build up your research capability.

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Caedo
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Re: How to defend against battleships and howitzers

Postby Caedo » Tue Jan 14, 2014 7:29 pm

I think you didn't take Hitpoints and Firepower into account.
The Battleship has 40 HP and 2 FP.
The Howitzer has 30 HP and 2 FP.
The Mech. Inf. has 30 HP and 1 FP.
Thus, in a fight between a Battleship and a Mech. Inf., the battleship's power is worth 2.67 times as much as the Mech. Inf.'s (because it has 1.33 times as much HP and double FP), which will make an elite Battleship probably win against the veteran Mech. Inf.
The Howitzer has double firepower, so even a veteran howitzer will probably win against the veteran Mech. Inf., and it'll be 50-50 with a veteran howitzer against an elite Mech. Inf.

Just saying.

clawsoon
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Re: How to defend against battleships and howitzers

Postby clawsoon » Tue Jan 14, 2014 8:05 pm

Edit: It might not be as bad for defenders as I've written below, because, from the help files, "If a ship is attacking a land unit on land the firepower of both is set to 1." In the scenarios below (defender has veteran status, city-center hills, coastal defense, is in a city), a veteran battleship has a:

- 51% chance against riflemen
- 22% chance against alpine troops
- 0.06% chance against mechanized infantry

That explains why I've had such good results with only 2 mech. inf. per city.

/end edit

That's a very good point. I've used a combat calculator, here:

http://www.longturn.org/warcalc/

...and you're right, things are worse for the defenders (much worse for riflemen and alpine troops) than they first appear because of the effect of hitpoints and firepower. Even with all the defense strength modifiers provided by city-center hills, veteran status, coastal defense and in-city status:

- riflemen will be defeated by a battleship 98% of the time

The battleship's hitpoints will be reduced by about half, which (plugging in the numbers a second time) gives a second riflemen unit a 50% chance of surviving a second attack from the same battleship. So, for each battleship you want to defend against, you'd need to have 3 riflemen units per city. If you want foolproof defense against a coordinated attack by 4 battleships, for example, you'll need 12 riflemen per city.

- alpine troops will be defeated by a battleship 92% of the time

The battleship's hitpoints will be reduced to 15, which (plugging in the numbers a second time) give a second alpine troops an 88% chance of surviving a second attack from the same battleship. Those are decent odds, so 2-3 alpine troops per city per battleship you want to defend against is probably enough. Let's say 8 alpine troops per city to hold off a coordinated 4 battleship attack.

- mechanized infantry will be defeated by a battleship 36% of the time

With two mech. inf. per city (plus veteran status, hills in city center, coastal defense), I rarely lose any units to battleships and have never lost a city.

Mech. inf. defending against howitzers comes out about the same as riflemen against battleships, i.e. not great.
I've never had a problem with AI howitzers, though, probably because I only build railroads where absolutely necessary. They can usually be picked off before they get to attack a city.
Last edited by clawsoon on Tue Jan 14, 2014 10:20 pm, edited 2 times in total.

clawsoon
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Re: How to defend against battleships and howitzers

Postby clawsoon » Tue Jan 14, 2014 8:32 pm

Sorry to respond to myself again: One more advantage of transforming your city centers into hills is that they're impervious to global warming. With habours (seafaring), offshore platforms (miniaturization) and city center hills, it's actually to your advantage to cause as much global warming as possible. Global warming becomes a weapon you can use rather than something to fear.

Once everything that's not a hill or mountain has been flooded:

- there are a lot more ocean squares, making celebration growth much easier and giving higher trade numbers because of the +3 trade per ocean square, which leads to faster research and more money.

- the number of landing points for attacking troops (howitzers, etc.) is reduced.

- many of your cities become disconnected, so attackers have to make a fresh landing for each city they want to take over. Each landing they have to do gives you a chance to counter-attack before they can attack you.

Once you want to start attacking, you'll have the same problems as a result of everything getting flooded. I avoid that problem by using bombers and paratroopers.

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JTN
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Re: How to defend against battleships and howitzers

Postby JTN » Tue Jan 14, 2014 8:32 pm

One nitpick:
clawsoon wrote:Even an elite battleship only has 12.0 x 2.0 = 24.0 attack strength, so you never have to worry about battleship attacks. You should hope for them, actually, because they allow some of your mech. inf. units to gain hardened and elite status.

Your unit's chances of getting veteran status are not affected at all by the veteran level, strength, hitpoints etc of the other combatant.
(I've considered implementing a ruleset option to allow it to be -- it's a bit silly getting high veteran levels by picking off diplomats -- but haven't thought hard about balancing it.)

clawsoon
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Re: How to defend against battleships and howitzers

Postby clawsoon » Tue Jan 14, 2014 8:46 pm

JTN wrote:One nitpick:
Your unit's chances of getting veteran status are not affected at all by the veteran level, strength, hitpoints etc of the other combatant.


Fair point. I've found that the AI seems to mostly try to attack my cities with battleships, which is why I expressed it that way. I assume it's weighing its chances of success with other attacking methods and finding them to be too low.

(I've considered implementing a ruleset option to allow it to be -- it's a bit silly getting high veteran levels by picking off diplomats -- but haven't thought hard about balancing it.)


Picking off diplomats is my favourite way to build up experience. :-)

Jim-11
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Re: How to defend against battleships and howitzers

Postby Jim-11 » Fri Jan 17, 2014 8:42 am

clawsoon wrote:It turns out that city-center hills don't help much against howitzers, so howitzers have to be defended against in the usual tactical way, i.e. attack them before they attack you and minimize railroads.

Howitzers are an impossible problem when trying to invade a continent with railroads and howitzers. With enough firepower, you can take over a city as a beachhead, but the howitzers immediately take it back. The only solution I know is to get to that continent before the AI can build howitzers, and the best offense is a good defense! Minimize early conflict so you can channel maximum resources into research. Then the AI will be unable to advance to difficult technologies before you can develop and build overwhelming force.

clawsoon wrote:Against battleships, though, the strategy works quite well.

If the AI gets battleships (and other warships), the best defense is to hide. :) Leave coastal cities empty if possible, and move all units away from the coast, so the warships have nothing to attack. If a coastal city must be staffed and defended, then having Coastal Defense (which is essential long before the AI can build battleships) and lots of Alpine Troops to sacrifice to weaken the battleship enough for your submarines or bombers to finish it off. If your research is advanced enough, Rocketry is the ultimate solution to defeating ships at sea.

clawsoon wrote:transform all city centers to hills (after you get explosives).

What is the secret to using Engineers to transform plains or forests back into hills? :?: I have not yet found the way to do that. :(

clawsoon
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Re: How to defend against battleships and howitzers

Postby clawsoon » Fri Jan 17, 2014 10:21 am

Jim-11 wrote:Howitzers are an impossible problem when trying to invade a continent with railroads and howitzers. With enough firepower, you can take over a city as a beachhead, but the howitzers immediately take it back. The only solution I know is to get to that continent before the AI can build howitzers, and the best offense is a good defense! Minimize early conflict so you can channel maximum resources into research. Then the AI will be unable to advance to difficult technologies before you can develop and build overwhelming force.


Agreed, minimizing early conflict is absolutely essential, especially once you start playing against Cheating mode.

To deal with the problem of conquering a continent of an AI civilization with Howitzers, I find it's most straightforward to build enough attacking units (either 3-4 Bombers per city + 1 Paratrooper per city, or 5-6 Bombers + 1 Paratrooper (for the beachhead) + 3-4 Howitzers per city plus enough Transports to carry them) to conquer the whole thing in a single turn. A couple of things that make that easier:

- Transforming your city centers to hills, putting offshore platforms in all your cities, and then waiting until the world has been flooded multiple times with global warming makes their continents smaller, giving you less cities to conquer per turn.

- Putting Shakespeare's Theatre in the right city can allow you to build up an attack force 50-150 units strong, even under Democracy. Figuring out the right ratio between Hills and Grassland+Irrigation (or, better yet, Grassland+Farmland+Supermarket) to create the maximum shield capacity is a fun exercise in itself.

Jim-11 wrote:If the AI gets battleships (and other warships), the best defense is to hide. :) Leave coastal cities empty if possible, and move all units away from the coast, so the warships have nothing to attack. If a coastal city must be staffed and defended, then having Coastal Defense (which is essential long before the AI can build battleships) and lots of Alpine Troops to sacrifice to weaken the battleship enough for your submarines or bombers to finish it off. If your research is advanced enough, Rocketry is the ultimate solution to defeating ships at sea.


I'm tellin' ya, city center hills plus Mech. Inf. (plus Coastal Defense) works wonderfully. :-) I've been able to completely stop worrying about attacks from the sea, as long as I get the Hills built in time. The AI sacrifices dozens and dozens of ships per game trying to conquer my coastal cities, and I don't recall losing a single Mech. Inf. from ship attacks, so long as it has Hills and Coastal Defense.

Jim-11 wrote:What is the secret to using Engineers to transform plains or forests back into hills? :?: I have not yet found the way to do that. :(


First you have to transform them to Grassland. You can transform anything to Hills, it just takes more turns. I usually build a couple of transports to move Engineers from the easy Grassland cities to the harder Tundra/Swamp/etc. cities once the Grassland cities are transformed.

How to make anything into Hills:

Glacier->Tundra->Desert->Plains->Grassland->Hills

Ocean->Swamp->Grassland->Hills

(Forest|Jungle)->Grassland->Hills

Mountains->Hills

Some of the steps require Transformation, and some of them require Irrigation. Oh, and mine the hills once you're done transforming, of course. It's a waste not to.

clawsoon
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Re: How to defend against battleships and howitzers

Postby clawsoon » Fri Jan 17, 2014 12:04 pm

I've attached a savegame from a recent game just after the hills transform + 2 mech inf, if you want to see it in action. Keep hitting "Turn Done" and watch the Messages to see how many AI units uselessly destroy themselves. Sell off the Eiffel Tower if you want to see more attacking.

When Global Warming happens, though, remember to check if there are any newly coastal cities which now need Coastal Defense and 2 mech. inf. That has caught me off guard a couple of times.
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City centre hills + coastal defense + 2 mech. inf. means no more worrying about battleships.
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