Attrition in Hearts of Iron 4 can be challenging to understand and deal with. The in-game tooltips don’t do a great job of explaining why it is happening, how you can prevent it, or even what it is. Well no more. This mini guide aims to fill in the gaps on attrition.
Attrition in Hearts of Iron 4 is the loss of equipment due to non-combat reasons. There are three types of attrition: supply attrition, terrain attrition, and weather attrition. Attrition does not cause a loss of manpower, only equipment.
Supply attrition is dynamic and is shown by a small red skull on your division’s icon. It occurs when your divisions are undersupplied. Units can be undersupplied for many reasons, but it is usually due to having too many divisions in a given area or the area having poor infrastructure and railways.
To deal with supply attrition either remove divisions from the area or improve the logistical capability of the area by building higher level railways, naval bases or supply depots, and improving the infrastructure.
Additionally, adding the logistics support company to your divisions can make a big difference by reducing their supply draw requirement. Finally, field marshals with the supply wizard trait reduce the supply draw requirement for units under their command by 15%!
Terrain attrition is static and is shown by a small white skull on your division’s icon. There is nothing that can be done about terrain attrition other than avoiding fighting in tiles that have it. Certain terrain like marshes, deserts, jungles, and mountains have a substantial terrain attrition rate. You can check the attrition rate for each terrain type in our land combat guide here.
Weather effects like mud, deep snow, and extreme cold and hot can also cause attrition. Having troops that are acclimated to the climate as well as a commander with the ‘winter specialist’ trait help to reduce this. There is no commander trait to reduce attrition from extreme heat.
Other Factors Affecting Attrition
Reliability plays a factor in attrition as well. Simply put, the lower an equipment piece’s reliability is, the more of it you will lose to attrition when it is present. Conversely, equipment with higher reliability will suffer fewer losses in attritional situations.
Additionally, when it comes to attrition, you need to remember that the number of different equipment types for a division template and their max count matters.
The more different types of equipment a division requires, the more overall equipment losses it will suffer due to attrition. This is because of how the math works behind attrition calculation. The short of it is that minimum attrition losses usually get rounded up to 1. This means that having a wide variety of equipment types or having equipment types with low max counts tend to suffer proportionally higher losses from attrition.
Say you have an infantry division that needs 1,500 infantry kits and 36 artillery. If the division were in an attritional situation, it would lose a higher percentage of artillery than infantry kits due to rounding and minimum losses.
In summary, to minimize attrition in Hearts of Iron 4 keep units in supply, keep division templates as homogenous as possible, avoid fighting in difficult terrain and weather, and use equipment with high reliability.
That is attrition in Hearts of Iron 4 in a nutshell. While suffering attritional losses is inevitable in warfare, after reading this guide you should be able to keep them to a minimum.