Explanation of what is going on under the hood to make the combat mechanics operate, like why your general is only attacking with 3 of 300 battalions or why you only captured one province after a battle.
Guide to Understand Generals
So you bought Victoria 3, you started playing, you got into a Diplomatic Play that escalated to war, and now you’re wondering why your generals aren’t doing what they want to.
This guide will cover some additional information from the game files that sheds a bit more light on what’s going on.
Fronts and Armies
There are two rules for how fronts are created:
- Fronts must be between two contiguous blocks of territories. When Mexico fights the USA there is one front between the USA and Mexico and one front between the Indian Territory and Mexico. The USA-Mexico front will be discontinuous because the Indian Territory-Mexico front is in the middle of it, but it’s still one front and generals will operate on both sides of it. If you advance and cut off a pocket of enemy territory, a new front forms around the pocket.
- Fronts are between exactly two countries. If you’re fighting two allied enemies there will be two fronts, one against each. If the Canadian colonies wind up helping Mexico fight the USA, the USA will have a front with each of the Canadian colonies.
In this example I only have one front with the East India Company, even though I have two borders with them. That’s because their land all connects together.
Each general can be assigned to exactly one front. If they advance or retreat and that creates a second front, then the generals on both sides will pick one of the fronts to fight on. If the enemy had two generals on that front and you only have one, then one of their generals will be able to push unimpeded. In large wars, then, it’s always better to have more generals than fronts in each theatre, so you always have someone to reassign if new fronts emerge.
Troops cannot currently be destroyed in encirclements in the game; if a pocket is cleared out, the generals defending it will move to the nearest remaining front. This is annoying when it saves an AI army, but helpful when it saves your army from a boneheaded mistake by one of your own generals.
How Battles Happen
If at least one general on a side of the front is set to “Advance Front” and there is no current battle on the front, then that side will gain progress toward starting a new battle. This is almost always +10 progress per day, reduced by 50% if the defending side has a general set to “Defend Front”.
When the meter reaches 100% then the battle starts. By default every province on the defender’s side of the front is equally likely to be the site of the battle. Provinces get their probability of being selected modified:
Capital Bonus is 10. Wargoal Bonus is 10 if the province is in a wargoal state; 6 if it’s in a state bordering a wargoal; and 3 if it’s in a state adjacent to one that borders a wargoal. This means that if you’re trying to take the enemy capital in the war, provinces in the capital state would be 100 times more likely to be the site of the next battle than other provinces with the same terrain and infrastructure.
Generally speaking, then, the battle is more likely to happen in high-infrastructure provinces with better terrain, and much more likely to happen in a province that’s either part of the wargoal or gets the front closer to a wargoal.
If neither side has a general set to “Advance Front” then the two sides will just stare at each other and take attrition. If your units are fully supplied and assigned to a front then they take an average of 2% casualties per week due to attrition. If they’re on “Stand By” then they’re living in barracks and don’t take attrition.
How Your General Picks How Many Troops to Bring
First the game picks which general is going to command each side. The generals are weighted by the number of troops they command, and the weight is increased if they have the corresponding attack or defence order.
Each side starts with a “baseline” number of troops. If the battle is happening on a regular front, this is the total number of battalions on that side of the front. If it’s a naval invasion it’s the number of mobilized battalions under the attacking general and the number of battalions garrisoned in the defending Land HQ.
The baseline is capped based on the terrain and combat width. The formula is:
Terrain Combat Width is a value between 0 and 1; it’s 1 in plains, 0.3 in mountains, and somewhere in between for other terrain types. So if the battle is in a state with 10 Infrastructure (common in low-population areas) and it’s happening in mountainous terrain, the cap is (5 + (10 / 2)) * 0.3 = 3 battalions. If these low-infrastructure mountains are the only place battles can happen on that front, then the baseline will always be 3 battalions for battles on that front, until it moves to better terrain/infrastructure.
Further modifiers are then applied to the baseline:
- If the attacking troops have average offense higher than the defenders’ average defense, then the defenders multiply their baseline by a random value between 1 and 3 that’s also limited by how big the difference in stats is:
- If the attacking troops have average offense lower than the defenders’ average defense, then the attackers multiply their baseline in a similar way, but limited to 2 instead of 3:
- These multipliers can’t increase the number of troops beyond the number available on the front. On the attacking side, this cap doesn’t include troops under generals set to “Defend Front”.
- Finally, the attacker’s number of troops is reduced to a random value between 33% and 100% of the previously-calculated amount, and the defender’s total is reduced to between 50% and 100% of the previously-calculated amount.
So as an example, for this front there’s a battle happening in some Plains:
It’s happening in the state of Hebei, which has 113 infrastructure right now in my game. So the terrain baseline cap for both sides of the battle is:
My Canadian troops have an average offense of 143 and the defending Chinese troops have an average defense of 43, so they increase their baseline:
This means China might have been able to bring up to 61.5 * 1.998 = 122.9 battalions depending on how well they rolled.
The attackers have better stats so they don’t get an increase.
Lastly, the attackers get reduced by up to two-thirds and the defenders get reduced by up to half. So Canada could have brought anywhere between 0.33 * 61.5 = 20.5 and 61.5 battalions, and 52 as shown in the screenshot was a pretty good roll for my generals. Meanwhile China could have brought as many as 122.9 (if they got the maximum value for both rolls) or as few as 30.75 (if they got the minimum for both).
The commanding general will always draw from their assigned troops before borrowing any from other armies on the same front. When they’re deciding which allies to borrow from, they’ll borrow more troops from their own country than from allies and they’ll prefer borrowing troops with higher morale.
How the Battle Is Won
Each round of combat inflicts casulaties on both armies. The attacking battalions inflict more casualties and receive fewer casualties if their Offense is higher than the defender’s Defense, and vice versa. The damage inflicted is scaled based on the remaining manpower of the battalion doing the shooting. Each battalion targets at most one battalion on the other side. I haven’t confirmed whether more than one battalion can pick the same target yet.
In this example I’m inflicting disproportionate casualties despite having been outnumbered over three to one at the start of the battle; this is due to the stats advantage.
Casualties can be either Dead or Wounded. By default 75% are Wounded and the rest are Dead. Some of the Wounded will rejoin their unit while others will become Dependents of a pop somewhere in your country. The number of Dead is reduced by having better Medical Aid production methods for your units, and it goes up if the opposing army has a higher Kill Rate (from better artillery PMs, Machine Guns, Flamethrowers, or Chemical Weapon Specialists).
In the screenshot above, 85% of my casulaties are surviving the battle, and only 74% of the Chinese casualties are surviving. This is because, while we both have good medical branches attached to our armies and giving a boost to Recovery Rate, my Kill Rate is a lot higher:
When a battalion takes casualties, it also loses morale. Morale is effectively a multiplier for the manpower of the unit; if it has 50% morale then half of its troops won’t be taking part in the fighting.
Morale is also reduced by having low supply for the army. This can keep an army stuck at 0% morale, in which case it auto-loses battles as soon as they start. You can push a front very fast when this happens, so convoy raiding to cut off supply to a front can be very powerful.
Battalions leave the battlefield if they are reduced to zero morale or zero manpower. The battle ends only when one side has no battalions left on the field; there doesn’t appear to be any mechanic for retreat before this point.
Battalions can reinforce during the battle, if the building they come from is able to hire people to replace the casualties.
What Happens After the Battle
If the attacker wins then they advance a certain number of provinces into opposing territory.
The number of provinces taken appears to depend on:
- The width of the front (the wider the front the farther the attacker advances).
- The number of battalions the attacker had left at the end of the battle (larger battle means more territory won).
- The density of the front (the greater the ratio of battalions to provinces is, the fewer provinces taken).
Some barracks Production Methods have an effect too:
- Trench Infantry and Chemical Weapon Specialists reduce the number of provinces captured by their army.
- Mechanized Infantry, Mobile Artillery, all of the Reconnaissance PMs, and Infiltrators increase the number of provinces captured by their army.
- Trench Infantry, Squad Infantry, and Machine Gunners reduce the number of provinces lost in a defeat.
So if you’re confident that you can win battles easily against your foes, selecting Chemical Weapon Specialists is counterproductive because you will still win with Infiltrators and you’ll capture land faster.
- You can’t start planning a Naval Invasion until the war breaks out.
- The fleet doing the invasion can transport exactly one army, and it needs to be an army commanded by a general who’s from a HQ in the same region as the fleet’s base.
- The fleet takes time to prepare (AFAIK it’s always 50 days) and then launches the invasion.
- If an enemy has a fleet set to defend the coast of the strategic region targeted by the invasion, then your fleet has to fight their fleet first.
- If your fleet wins, then the army being transported starts the land battle. It will be facing any and all armies currently Standing By or garrisoned (not mobilized) in the same strategic region as the invasion target state.
- If you haven’t researched Landing Craft (Military, Tier IV) then your army takes a large penalty to offense during this battle.
- If your army has more battalions than the supporting fleet has flotillas, then the army takes another penalty to offense, scaled based on how many more battalions that ships there are.
- If your army wins then you capture some land and a new front opens. Then you can assign additional armies to this front.
- Having all your troops under one general or splitting them up to be under several generals doesn’t affect the number that join a battle. The only reason you’d want to concentrate troops under one general is if he has really good traits, since a general doesn’t give any boosts to troops he borrows from another commander.
- Having multiple generals assigned to the front means that you can more easily handle unexpected front line splits. If your generals are of equal skill to each other then this is a good idea.
- If you keep having battles with only a tiny number of troops engaged, it’s probably because you’re fighting in bad terrain and/or bad infrastructure. You cannot fix this by adding more troops, only by moving the front line out of the bad terrain/low infrastructure. Consider focusing on another front, or launching a naval invasion to open up a new front that’s easier to push. If you’re the war leader, you can also use Violate Sovereignty to demand passage through a country that borders you and the enemy war leader, and invade them if they refuse; this will create a new front either way.
- If you know the whole front is bad terrain and low infrastructure, don’t send hundreds of battalions to it; they’ll just be sitting around dying of typhoid or whatever it is that causes attrition.
- Having more troops than your opponent does provide a second advantage beyond possibly being able to outnumber them in battle: it means battalions that lost morale will have a chance to recover it between battles, rather than constantly getting selected for another battle less than a month after the last one ended.
- Don’t use Chemical Warfare Specialists unless you absolutely need the extra offense and morale damage that they provide compared to Flamethrowers or Infiltrators. They slow your advance down significantly.
- To do successful naval invasions, you want to have some large fleets and you want to make sure that the HQ the fleet is based in also has an army that’s got roughly as many battalions as the fleet has flotillas. If the army is much bigger, it’ll have bad offense. If the army is too small it might be too weak to get a beachhead. If all your fleets are small, none will be able to transport a significant invasion force.
- You should also be prepared to have a lot of trouble with naval invasions until you research Landing Craft, as the offensive penalty is pretty severe. This is less of an issue if you’re confident that the defender doesn’t have many troops left Standing By or Garrisoned in the target HQ though.