Many people seem to value Cavalry and mobile offensive units as the best way to break open besieged enemy cities. While I can see this working in Medevil times and once you have tanks, there is that curious gap in the offensive tech tree that is know as the industrial ages.
Since Replaceable Parts can be researched quite early in the Industrial age and it gives you the 6/10 infantry, there can be a long period where the defensive units have a strong advantage over the offense ( 6/3 Cavalry , which doesn't actaully have any better offensive stat than the infantry ). You get trench warfare very much like WW1. Many suicidal charges are needed by infantry and cavalry just to kill one defending infantry, especailly if they are in a large city
This post explains my method for conducting reasonably fast, very efficient war in this tech environment.
Firsty identify why you are in this war :
a) They started it and you want peace. You're stalling until they will talk to you.
b) Limited war to get a specific objective: a resource or a clearly defined chunk of territory. Also you might just be punishing them for starting a war, but be clear how far you're going to punish them.
c) You plan to drive them into the sea and own all of their land.
All of these scenarios can be handled with variations on the same theme: the AI does not understand railroads and does not understand artillery (which becomes available with replaceable parts at the start of the age of trench warfare). All of the tactics below become more effective the larger the map is, as you have a bigger empire's troop output that you can concentrate just as effectivly using railroads.
So what units do you have available ?
1. Horsebased units upgraded to cavalry. Nice to have hanging around but don't bother building any more, as they're going to be obselete soon and they're not key to the plan.
2. Infantry. Very hard for the AI to kill. Makes your cities very hard to take. Slow to move around, so you want lots spare. Also they're actaully going to be doing a lot of the attacking, so you'll be loosing some of them. 50% of your unit producing cities should be making infantry. All of these cities should have barracks
3. Big Guns. Artillery. Upgrade all those old cannons and catapults (small point here - cannons can't do mountains, artillery can).
You just cannot get enough of these. 50% of your unit producing cities should be producing these. If you find that you're not loosing too many infantry then up this % to 60 or 70 %. These cities don't need barracks as there's no such thing as a veteran artillery.
The arguments about alliances / RoP and such like we will leave, as they belong in a discussion about diplomacy. They are important, but lets just stick to the tactics of war here.
There are 2 themes we use :
Firstly, your large stacks of artillery can hit any tile in your empire and any tile within 2 moves of your borders at will. This is becuase you've buit a good rail network , right ? The firepower will be delivered without mercy, and any stack of guns will be covered by at least 3 infantry. Armies of infantry can be good for this role, as you don't care if they can't attack as frequently as solo units : they are there as a deterrant.
Secondly, fortified units in cities are very hard to kill. Units moving thorugh open ground are much easier to kill. Any unit that you place in the open ( especailly if it got hurt fighting ) should get a 4 hp infantry escort. Any unit of theirs that shows its face should be gunned down with no mercy. This is after all trench warfare, attrition is king, and anything you can kill easily is much better than letting it get fortified in a big city.
Now the actual tactics, depending on which warfare mode you are
in.
a) Defensive war mode. You are numerically inferior to the opposition, so don't plan to make inroads into his terriroty. He will dutifully send stacks of units at you. Try to hold the hills and high ground near your border with stacks of infantry + artillery. Shred as many units of his to 1 hp with artillery fire as possible. Even if you lack the units to actaully kill them afterwards then they are knocked out of the offense and will be retreated to heal. All your artillery should be moved into firing positions and fired every turn. If you run out of targets, save the spare artillery until the end of the turn. Sometimes you'll attack a 1hp infantry with one of yours and still loose, and their infantry gets promoted, thus gaining 1hp. Use your spare shots to put them back down to 1 hp. If you still have spare shots then take out the railroads an roads across the border in his empire to slow down the offense and slow down the recycling of damaged units. If you feel you have some spare infantry / cavalry for offensive raids then use them to attack his 1 hp units. Start with is cavalry ( since its alrady been bombarded to 1 hp it can't retreat from your infantry ). If you get on to killing his 1 hp infantry then take the units on plains / grassland / desrt first. Be very careful about attacking across rivers and attacking fortified infantry. As soon as his 1 hp infantry gets dug in or in hills then there is a small chance your 4/4 infantry will loose, and the whole idea here is to inflict attrition while sustaining minimal actual unit losses yourself. Use his stacks to keep your units in position.
Eg , you have 15 artillery guarded on a hill by 5 infantry and he has moved a stack of 6 cavalry to the adjacant grassland. More cavlary and infantry is coming up behind. You have 2 spare cavalry on your rail network. Fire all the artillery at the cavalry until they are 1 hp each. Draft in more Artillery from elsewhere if you have it and need to. You can probably afford to unfortify 2-3 infantry. Attack with these, killing the 1 hp 3 def cavalry. Attack with your 2 cavalry as well. Don't kill the last 1 hp cavalry, as this will pull your attacking unit off your defended hill and into the open. If you don't have a spare cavalry available to kill the last unit in a stack ( ie attack and retreat again ) then let it live. You have inferior numbers so need to preserve every unit you can.
This tactic also forms the basis of B) Limited war , and C) Total Annihilation war when mopping up his counter attacks. The first 5 or so turns will probably involve much of your artillery shattering his counter attacks, and not much taking of cities, but this phase will pass as you slaughter his offensive troops and take light losses yourself.
This method can be used to hold an enemy with many more troops for many turns. In the end he will agree to peace and you won't have lost too many troops or too much progress vs the rest of the world.
How you take cities in limited and total war :
Its the same basic method for both.
Points to note about defended cities :
1. Defenders get 50% bonus if pop > 6 and 100% bonus if pop > 12. They also get 50% bonus if the city is on a hill, 25% bonus of you attack across a river, and 50% bonus just for being fortified.
So infantry fortified in a size 15 city on a hill has an effective defense of 10 + 10 * (1 + 0.5 + 0.5 ) = 30 !!!. Verses any of your attackers with attack 6 then theu will win 5 / 6 combat rounds. Your 16/16 army of cavalry stands a better than even chance of dying against a single 4/4 infantry !!!
2. A beseiged city will draft futher infantry. It can't do this if the popluation is <= 6
3. A damaged defender will recover all his hp if fortified in a city with barracks.
So how do you deal with this massively powerful defense ?.
Artillery. Guns. Shooting big shells. Bombardment. Lots and lots and lots of it. You just can't get enough, its like Cholcolate or MTV. Too much is never enough. I tend to deal with artillery in my offensive phase in stacks of 20 +. I have been known to fire 50 shots at a single beseiged city and then choose not attack it that turn.
When to attack a city :
1. Pop <= 6. If you plan to keep the city then it pays to bombard it all the way down to 1 pop, then you hardly ever get culture flipped.
2. Best defensive unit showing has 1 hp. Ideally the barracks will be destroyed if you are in a multi turn bombardment.
This takes a lot of shooting. Patch 1.17 raised the building and population defense vs bombardment to 12. When you fire at a city it seems to randomly determine if you target a building, a defender or a pop point. If the pop is already 1 and all the targetable building are already gone them you can still target them, and your bombardment attempt fails on those shots. Getting the last 2 infantry out of a ruined town can take a lot of guns, but if you have to shell then for 3 turns, so be it, at least you are not loosing units and they have all but lost the use of that town in terms of production, culture and population.
Once you are attacking it make little difference if you use cavalry or infantry, as the opponemt has 1 hp the cav won't retreat if they're loosing anyway. Lets revisit our beseiged hilltop town from earlier:
Pop is now down to 4, we know there are 4 infantry in it because we were paying attention as our 30 artillery damaged each one in turn. The barracks have been destroyed (actually everything has pretty much destroyed, though we suspect there might still be a marketplace standing). The defending infantry now has only a 100% def bonus , as we have reduced the pop from 15 to 4, so a total effective def of 20. The infantry will win approx. 75% (20 / (20 + 6 )) of rounds vs our attacker, but it only has 1 hp, so must win 4 rounds in a row to actaully win the battle. Better still we migh be bringing some elite untis to the party. P(win vs vet) = 0.35 for the defender. P(win vs elite) = 0.27. Yes , you will loose some units taking the city, but probably only 1 or 2, and he has actually lost more infantry in the process than you have.
Even better is the fact that half taking the city doesn't actaully cost you anything. If you half take a city by throwing 10 cavalry at it and don't complete the job, then next turn you'll be looking at more healed / drafted / reinforcement defenders, and you'll have 5 dead cavalry and 5 1 hp cavalry. If you bombard the hell out of the town and it doesn't get reduced enough, you just sit tight and repeat next turn. If you really have bitten off more than you can deal with them you'll find that his counter attack forces you to retreat the artillery from the siege and use them to crush to offensive, smoothly transitioning you to a defensive war of attrition with very little pain.
Some words on Manoeuvre :
Infantry and artillery are slow, but railroads make up for this.
Railroads only work for you if they are outside the enemy terrirory, so clearly there is some slow moving to be done to actually take enemy cities. Some pointers.
1. Unless you are totally on the defensive, don't take out roads and railways in the enemy territory - they'll be yours soon enough and you're going to need them to jump your artillery around the place.
2. Artillery have a 2 tile rage. Somtimes they can hit the enemy city while still on a railroad in your territory, particularty in the opening phase of the war as you fight from across the original cultural boundaries. Often your artillery can reach a firing location only 1 tile into the enemy territory, so you plan 1 go ahead, choose a city to take , move gun stack 1 tile into enemy land, add 5 or so infantru to keep them protected, and fire away next turn. Once you leave your territoy your guns and infantry are only moving 1 tile anyway, so you might as well move them onto hills or mountains if any present themselves. Keep them on the enemy roads or railroads however, as once the enemy city falls the terriroty will be yours and you don't want to waste a turn just getting your stack back onto the railroad network. Higher ground also means to can see what effect your shooting has ( see point 4 ).
3. The attackers. Its easy to get in a situation where your gun stack has wrecked their city from 2 tiles away, but no attackers are on hand to deliver the killing blow. Forward planning is needed. Always have in mind which city you plan to move onto next. Bear in mind that is might not be next to the city you're currently working on. Your rail network allows you to switch your next attack to a city at the other end of the front. Also remember that the cultural borders shift as you take a town. If you are looking at moving on a city next to the one you have nearly taked, then play out the attack on the city you expect to take this turn first. Then you can see how the cultural border has shifted, and which railroad tiles now belong to you, then move making full use of the newly take RR tiles and attack the next city.
Often you will have a turns lag at the various units move through enemy tiles into position. 2 possiblilites :
Small gun stack - you'll need multi turn bombardment to reduce the target city.
Turn 1 - Guns and escort move into firing position.
Turn 2 - guns fire, escort infantry move adjacenmt to target city. Additional infanty move onto guns to protect them.
Turn 3 - gund fire, infantry take city (if conditions are met to assault the city). RR tiles become yours, spare guns move to next fire location......
Large Guns stack ( Depends on defenses... but 25 + is beggining to be large - only one turn of firing will be needed.
Turn 1 - Infantry forward assault team move in to enemy tile. Guns are still busy shooting at previous target.
Turn 2 - Guns move to fire location with escort. Forward assault team move adjacent to target.
Turn 3 - Guns fire, forward assault team take city. If the ground to be covered is flat then you can dispense with some of the assault team if you have enough cavalry to deliver the killing blow.
4. Try very hard to have a unit who can see the results of your bombardment. Either use high ground or a "forward spotter" infantry. This allows you to see how many defending untis there are, and when the last one is reduced to 1 hp so you can attack.
5.Be careful with rivers. They are easy to overlook and can swing the defenders chances higher. Plan your manoeuvers well.
6. Cavalry. Since they have 3 movement they can provide a flexible shock assault squad without planning movement turns ahead. If you had a stack of infantry assigend to take a town and they have a very bad battle ( or you messed up the planning ) then the enemy city might be left standing with a single 1 hp defender. You just know you're going to be looking at another 3 defenders next turn, so now the few cavalry you own that were held in reserve on your rail network can swing in and save you a turn or 2 of re-bombardment.
-snip-
......see next post
), so that I will still have a modern army than my enemies.
I build a huge artillery group and bomb the heck out of invading armies. Then I build infantry. It works in stopping invasions.
