Do commanders and army composition even matter?

[YouWeiDe]

I played several games on ck2, and i think i understand how most things work in general, but today my questions are about army and combat.

The army composition , technology level and even the leader traits seems not to matter. Almost always the bigger stack wins, regardless of how their flanks are organized. Of course if one army has leaders and the other does not it's less likely for the leaderless army to win even if they have numbers advantage.
My question would be how to make the army composition, commanders and traits more influential in the war/battle situations? Is harder difficulty the only way to change that? Cause if i remember correctly AI gets some unfair buffs in harder difficulties. I am usually playing on normal. And due to this higher numbers win situation i usually just make people i don't like or need into commander with the hope they would die. Annoying vassals or terrible heirs usually. Almost never bother with anyone getting proper military education.
I know this is more political intrigue kind of game, but currently this whole stack vs stack makes it feel like it's conquest game were numbers matter the most. Every time i raise levies, i just combine them into one huge stack without much thinking and attack directly.

This is not a rant or anything, just maybe someone can give me their opinion and insight. Maybe i'm overthinking it.

 

[Andrew0Red]

Tactics and army composition is complicated. https://ck2.paradoxwikis.com/Combat_tactics

But a way to start (assuming you're feudal) would be to use retinue entirely of Defense Retinues (200P+50A), and organise your army so they comprise a flank of their own. Then give them a commander with 12+ or 16+ martial to get the best tactics. If you can get a commander with traits that benefit pike, do so (traits are more important than high martial). If you can get a scottish or italian commander for the pikes, do so.

A longer version:

Light Cavalry, Archers and Horse Archers are skirmish troops. They have better stats in the skirmish phase and worse in melee (they also tend to be good in the pursuit phase). Heavy Infantry, Pikemen and Heavy Cavalry are melee troops. They have very good melee-stats, but stink in the other two phases.

Then there's tactics.... LC, A and HA each have their own tactics in the skirmish phase, plus the three hybrid tactics. A pure tactic might increase LC attack by +300% but reduce A and HA attack by -150%. A hybrid tactic might be LC +250%, A +150% and HA -150%. In addition there is some rock-paper-scissors; the HA tactics take +100% damage from the LC ones, LC tactics take +100% from A, and A tactics +100% from HA. As you see, having LC makes A and HA worse, having A makes HA and LC worse, &c. Thus, it would be best for each flank to only have one type of skirmisher, but we're limited in which compositions we can choose.

In melee, HI, P and HC works similarly, but the rock-paper-scissors is +300%.

 

[jonjowett]

@Andrew0Red has discussed troops and combat tactics already, so I'll take up the other part of your question.

Commanders definitely matter.

To take an extreme example: If you build your character "correctly" over a couple of decades, you can lead your troops to victory against insane odds (eg. outnumbered 10-to-1, and suffering from river crossing and mountain penalty).

The reason this extreme example works is because certain traits give small bonuses to your troops - eg. Cruel gives +10% morale damage. What the game doesn't explicitly tell you (although it's documented in-game in tooltips and on the wiki) is that all of these modifiers are further adjusted by "martial influence", which is a multiplier of (1+0.05*martial) - eg. a character with 20 martial will have a martial influence multipler of 2, which means that the Cruel trait will give +20% morale damage and Organizer+WayOfTheTiger will give +100% movement speed.

So, if you find a high-martial (30+) character with useful leadership traits then that character will have a VERY LARGE effect on your troops.

The best sources of these extreme-martial characters are the bloodlines that have the "great warriors join your court" feature. IE: If you're playing in Europe, Catholic Karlings are very useful, because every landed Karling will continuously generate amazing commanders.

Spoiler: Explaining how the borderline-exploit works

The borderline-exploit mentioned above occurs when a player character boosts their martial into the stratosphere while also collecting 6+ commander traits (warrior lodges!) and a ton of artifacts. Then, move all the troops in an army into one flank, and set your character to lead that flank. Enemy armies melt almost instantly.

Here's an example - terrain specialisation everywhere, and massive improvements to so many other things that it overflows the tooltip:

That said, I usually prefer the simplest approach - overwhelm the enemy with large numbers of mediocre troops; teleport in the uber-king if there's a difficult battle; and otherwise focus on commanders that improve strategy rather than tactics. (By "improve strategy", I mean I want them to have traits that give improved siege speed or movement speed or winter supply limit.)