Europa Universalis IV - Development Diary 24th of May 2022

Hello everyone, Gnivom here today.

I may return for a future dev diary on the many AI improvements we’re making for 1.34, but today’s topic is Land Combat.

First a recap:

For 1.33, we decided to change some things with combat; first mentioned in this January DD and soon amended by making backrow regiments take 60% less morale damage. The core idea was to remove some weird traps that uninitiated players (I would guess a majority) and the AI (without major modifications) would easily fall for. In particular, having a large army without a full back row of artillery could be disastrous.

However, those changes also caused some unintended balance effects:

1. Battles last longer, sometimes a lot longer.
2. Morale is much less important.
3. Stackwipes (officially “overruns”) are much less common (though this is mostly caused by the AI accidentally exploiting the Zombie Regiments bug, by shift-consolidating troops before battle).
4. Tech Groups’ impact through unit pips have been amplified. This has not been addressed so I won’t mention it again in this DD.

Additionally, some of you have pointed out that what can be seen as a “noob trap” can also be a source of tactical depth in multiplayer.

Now, let's look at what's new for 1.34 and how this addresses these issues.

Passive Morale Damage​

In 1.33 we made the daily 0.03 “morale damage to reserves” actually only apply to reserves, where it previously applied to deployed troops as well. The intention was to relatively penalize overstacking more as well as to be consistent with the name.
This is a major cause for the longer battles in the early game, and for morale being less important, and has now been reworked in 1.34 to as follows:

• Deployed troops take a daily morale damage of 1% of max morale.
• Reserves take a daily morale damage of 2% of max morale.

Only the reserves are affected by the Professionalism modifier, so it remains mostly a QoL modifier, although its absolute effect is now much bigger.

Max morale is not based on the regiment itself, but on the average of all regiments on the other side. Such that, in a standoff between a Prussian and a regular soldier, where neither is shooting, the regular soldier will run first.

The fact that this is now a percentage means that its importance will be consistent throughout the ages, so that late-game battle length is now shorter.

While on the subject of morale, some of you may know that when entering a battle against someone with higher morale, your morale progress bar starts at less than 100%. This is now changed to show the percentage of your own average max morale, rather than the max of all regiments on either side. This makes it easier in my experience to guess who is winning from just looking at the bars.

Zombie Regiments​

As mentioned above, EU4 has always had a bug (feature?) called Zombie Regiments.
In 1.34, regiments will always retreat and be replaced once either strength or morale reaches 0, removing the 12 day invincibility.

Additionally, an obscure condition for stack wipes based on the remaining morale of defeated regiments has been removed. You probably didn’t know about it (I didn’t), but it started mattering when 0-strength full-morale regiments were immediately retreated.

All in all, stack wipes are now much more viable than in 1.33, but still less viable than in 1.32 if the losing side has more than a full front row of decent-morale troops.


Adding a screenshot here for future readers, as the wiki link may be obsolete.

Insufficient Support​

Insufficient Support currently works by applying a flat -25% Military Tactics to all troops of an army that has too much cavalry, even if it’s just 1 knight above the limit. Although it’s made a bit more complicated by counting armies from different countries separately, as well as mercenaries.

In 1.34, this will instead be a scaling penalty of -1% Tactics per percentage point of cav/inf ratio above your limit. The ratio will be calculated based on all deployed front row troops on your side, while the limit will be calculated individually per regiment. Only cavalry gets affected by the penalty.

Two things to note:

• A country with a high support can still cause allied cavalry to lose Tactics.
• If you overstack your armies, an overall balance does not guarantee a frontrow balance at every moment of fighting.

Correction: A previous version of this post erroneously talked about "Combat Ability" instead of "Military Tactics"

Artillery Pips​

Artillery unit pips have been rebalanced.

• Late-game artillery will have less defensive pips and more offensive ones, contributing to shorter late-game battles.
• Techs 7, 10 and 13; which give two options; now have a distinct difference between the two, where neither is strictly superior to the other.

(compare with current values)

Let me take this moment to briefly explain an existing feature: for each damage calculation, backrow artillery propagates half of the sum of relevant defensive pips to the regiment in front of them (rounding down). For example, the Leather Cannon will propagate 2/2=1 pip to strength damage calculation in the fire phase, and 1/2=0 pips during shock phase. For morale damage, it will propagate (2+1)/2=1 pip during the fire phase and (1+1)/2=1 pip during the shock phase.

With this feature in mind:

• At tech 7, you choose between winning battles quickly (Mortar) or dealing strength damage (Houfnice).
• At tech 10, the Pedrero is your anti-cavalry weapon by propagating 1 shock defense to the front row. But the Culverin deals more strength damage.
• At tech 13, the Small Cannon propagates 1 morale defense to the front row in both phases, but the Large Cannon will deal more damage (to both strength and morale).

Reinforcement to Back Row​

This change in particular is still subject to further testing, tweaking and possible removal.

Reinforcement to backrow means something very different now vs in 1.32. In 1.32 it was a way to push further infantry/cavalry into the death pit that was the back row. Only after all inf/cav reserves were spent did artillery reinforce to the back, and once there they never left.
Now (since 1.33) only cannons can be in the back row, and they can also retreat from it, which makes back row reinforcement an important (and positive) thing.

From 1.34, each combat side will be limited to 2 back row reinforcements per day, plus 1 per 2 maneuver pips of the commanding general. This does not limit initial placement of artillery at battle start.



This is intended to increase tactical depth in multiplayer, by a number of means:

1. Armies caught low on artillery are more vulnerable, though not as badly as in 1.32.
2. Cavalry becomes more useful during two distinct phases of the battle:
   1. Just after the initial line of artillery retreat, which happens roughly simultaneously.
   2. Later in the battle, when the combat duration modifier is so high that artillery reinforcements can’t keep up with churn.
3. This breaks the symmetry of long battles, so that artillery (and by extension, infantry/cavalry as well) don’t all retreat in huge batches.
4. Quality becomes more important over quantity in long battles, as high quality troops will lower the “artillery saturation” of the enemy.

Breakthrough​

After some initial testing and discussion, this feature will probably not make it into vanilla, but it will be available for modders to enable.

• Two defines have been created: INFANTRY_BREAKTHROUGH and CAVALRY_BREAKTHROUGH, each being a probability between 0 and 1.
• When defeating a regiment with artillery behind it, you have a probability (equal to the corresponding define of your regiment) of pulling that artillery into the front row.

If we don’t change our minds, and if you still choose to enable this, there will be no UI or tooltip mentioning this whatsoever.


Well, that’s all for today!

Next week, @Ogele will return with a Dev Diary showcasing the new content we’ve been creating for the first country in the Scandinavian region: Denmark, and its troubled lead over the Kalmar Union.