Hearts of Iron 3 Dev Diary No. 5

Lead Developer Johan Andersson talks HoI3 here at Giant Realm.

Hello, and welcome to the fifth chapter of the Hearts of Iron 3 development diary. We’ve had yet another busy week developing lots of interesting things for the game. Today we’ll talk about basics of the land combat system in HoI3.

Land combat, in our opinion, forms the centrepiece of Hearts of Iron 3; the whole game revolves around your ability to take provinces from other countries. Thus combat was an area we put a lot of thought into and the basic system was one of the first game features we coded in. Our overall goal was to take an already good combat system and make it better.

First up, move is still attack. It worked in Hearts of Iron 2 and we felt no reason to change to this basic system. However, we added a movement penalty when you are fighting which can be increased or decreased according to combat events. Now it is possible to use small units to try and delay an enemy. However due, to the unpredictability of combat, you don’t know in advance how successful they will be.

The next thing we looked at was the legendary super stack. Not to say the super stack doesn’t have its place, but we made sure to change it so that now it is no longer a guaranteed success. We added a maximum attack frontage, per attacking province, which feels a bit like the EU3 or EU: Rome battle screen. There are now only a finite number of units that can attack or defend on a single province border. First, as you no doubt remember, we actually have several sizes of provinces. We have assumed that all provinces are the same for attack frontage purposes. We justify this assumption on the grounds that these large provinces are usually in places in the world that are remote and have hostile terrain.  So even though the borders are technically larger the terrain, you cannot use this extra space to bring more units into combat.

So what does this mean? First off, if you cannot fill your whole frontage, you suffer a force-to-space ratio penalty. From the point of view of an attacker, the more provinces you attack from, the more likely you are to stretch the defenders and force them to thin out their lines. This means that multiple attacks are good, but you can’t just throw in a single division and pick up a nice bonus.  You really need to attack with numbers on each axis.

The next question is how much space does a unit take up? Well this depends on the unit composition of the division - the more brigades a division has, the more frontage it will take up. It also depends on doctrines. For example, the Blitzkrieg path gives you the ability to narrow the frontage of armoured units, making them more effective. Finally, terrain also affects the frontage - when crossing a river or making a seaborne landing, it is much harder to bring your massed troops to bear as compared to nice open terrain.
Onto the next question, what happens to the extra units? They sit in reserve. If a unit drops out of the front lines, there is a chance, modified by things like doctrines, that it will join the combat. If you run out of troops on the front line, you may have your troops retreat regardless of the number of reserves.

To sum up, a large stack is no guarantee of victory. Not all these units will be able to fight and there is a chance that not all of them will even get a chance to fight. Combat should become much more unpredictable, and quality should be as important as quantity. You might blitz your enemy or you might end up in a grinding attritional fight that drags on.  The goal is to remove the “I win” option out of combat and make your strategy much more important than the size of the stacks. People on the home front want victory, not super stacks. 

Here is a screenshot of the mighty Swedish army, all ready to invade the Norwegian forces, to reunite them, in the utterly historical war of 1936.


Johan Andersson is Lead Developer of Hearts of Iron 3.

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