Hearts of Iron III lets you play through the most engaging conflict in world history, World War 2, on all fronts, as any country and through multiple different scenarios. Guide your nation to glory and wage war, conduct diplomacy and build your industry between 1936 and 1948.

Hearts of Iron 3 Developer Diary # 9 – Naval Combat

Welcome to the 9th chapter of the development diary. We are continuing working on naval combat, and developing various logics to how naval units behave. It is also rather exciting to see the progress of the new espionage system.

Probably the truest maxim in war is that amateurs study tactics and professionals study logistics. When coming to do a game of the scope of Hearts of Iron 3 we knew that logistics would have to be one of the key constraints on your actions. However at the same time we aren’t making World War II Logistics Manager: Deliver Shells for the Fatherland, so although it should be important we felt that it should not be the be all and end all of the game.

[Just a note on terminology here, we have fuel and supplies. However through out this developer diary I am simply going to refer to both of them together as supplies.]

With this philosophy in mind we have totally rewritten the logistics system, there is no longer TC. Instead supplies move from your capital out to your units. The amount of infrastructure in a province acts as a limit to the amount of supplies you can move. The supplies advance on a daily basis. In addition there is a supply tax, the further your unit is from its supply source the more supplies it consumes. After all, supplies don’t move themselves; you are going to need people to move them, who in turn also consume supplies. In addition each unit carriers a small amount of supplies with them, if they cannot draw supply they will start to consume these instead. Like Hearts of Iron 2 if a unit is abroad it will have a supply stockpile point that acts as a base for its supply. However there is one additional factor, when convoying supplies abroad the maximum amount of supplies you can send is limited by the size of port. The bigger the port the more supplies you can ship in. The control of ports is very important if you wish to wage campaigns overseas.

So let’s talk a little about what this means in practice. First off, and sticking with our design philosophy, the actual nuts and bolts of delivering supplies to your units is automated. From the player perspective, logistics is something you work with not something you have to constantly manage.

When it comes to the actual supply itself the most important thing to remember is that supply lags, how many supplies a province asks for is based on how many it needed yesterday. Thus your ability to simply mass units for an offensive are limited by the fact that it will take time for your supply network to adjust. Since this request then needs to ripple back down through the supply network, you need time to prepare your troops for an offensive. This in turn gives the enemy a better chance to detect and prepare for it via intelligence. Also, coming back to that recurring theme of the superstack, with it now being possible to only deliver a finite amount of supplies you can no longer stack unlimited units in a province, especially not one sitting out in the middle of no where.

When advancing you start to devastate the infrastructure, dramatically reducing the amount of supplies a province can draw. Although given time infrastructure will recover, in the mean time the unit will start living off the supplies it is carrying. Sooner or later you are going to have to halt to allow your supply lines to catch up. When defending since your units have supplies and each province also has supplies, it means if your units are encircled they are no longer just simply out of supply, they will have a number of supplies inside the pocket allowing them to fight on for a while.

This system also puts new life into the logistical strike mission. Bombing infrastructure behind enemy lines will reduce the capacity of their supply network. Making it harder to keep their units at full fighting efficiency. Logistical strike missions can assist either the attacker or the defender, because troops always need supplies.

Technology is also your friend here. One of the logistics techs you can research will improve the number of supplies you can draw per level of infrastructure. So as you improve in this area which choice do you take? Do you use your improved supply capacity to put more units into the front lines to improve your punch on the offensive, or do you use the same number of units but with your improved draw ability sustain the advance that little bit longer? Well that’s what strategy is all about, the choices you are faced with.

I know we’ve sort of rambled on a bit here, but the logistics system was something we put a lot of work into designing and implementing and we are really pleased with the results.

Here is an example of the logistics mapmode, where you can see how the supply networks in France are going, while you also see the convoys going to and from France proper, depicted with arrows

Johan Andersson, Producer of Hearts of Iron III