You do realize a battalion is much smaller than a regiment or brigade yes? If so I'm not sure I follow your logic in the reply to what i wrote.
That divisional sized partisan units making a show and occupying territory and fighting battles on any relevant scale was pretty uncommon throughout the entire war is not something anyone made up (it did happen but so did a lot of other things like B-24s attacking Tokyo from an aircraft carrier). The fact that this is portrayed in HOI3 but not in HOI4 is about a relevant discussion on realism as the lack of battalion sized units or individual aircraft production in HOI3. Battalion and Brigade combat action was a key piece in WW2 but the scale is insignificant in a grand-strategy title and so are multiple uprisings of a couple of thousand guerrillas for the exact same reasons. There's simply no mechanics available to handle it so it's abstracted just as a lot of other things. It was tested in HOI3 and it didn't work out without becoming whack-a-mole for the players and AI and so I fully understand PDS decision not to include it in the first iteration.
I would love to see smaller scale engagements if the mechanics could support them and if it doesn't create micromanagement hell for players. It would for example make Weserübung and the fighting in Norway both more interesting and operationally relevant on a realistic perspective as well as many other engagements but if resistance movements and small scale engagements are abstracted for core-game playability at release I'm fine with it.
I have not said battalions, I said regiments. Battalions I mentioned as a basis of organization as Royalist resistance in Yugoslavia took that from pre war specialized guerrilla formations for the basis of its organization. Yet battalions never fought by themselves - they were too small. Regiments did. Most of the time with a few other regiments (constituting a joint command as a division), rarely if ever a single regiment. Yet in HOI4 you have that option - "division" that has only two regiments. I do not know if one is also doable but two regiments yes. We have seen it in the last WWW.
So what is the problem in having a division comprising of a few militia regiments that was the case in Yugoslavia and Soviet Union?
As I said, HoI mechanics worked like a charm! And before you jump on it, let me explain.
First, you had static modifiers - revolt risk. That made an impact on your IC and resources generation from a conquered province and added to the supply cost transfer - all of those things are represented in HoI4 with its partisan mechanics. And I have absolutely no problem with that. It is as it should be.
Second, you had covert operations. And THAT is your target driven sabotages of infrastructure and strategic resources. Blowing up of Norsk Hydro and so on.
Third, you had underground cells. Those provided intel about the enemy and could be destroyed.
Forth and last, active resistance. When you think you have it prepared you could launch the revolt (for what ever reason) and free the territory. Just like it was in reality.
Of those 4 things, we have now 1.5 with underground cells integrated in general partisan mechanics.
Now, where is the problem with that system? Firstly, you had additional partisans out of your control - those black formations that did not fight. You just had to attack them and they would disappear. That was that wack-a-mole problem, not the AI/player controlled partisan system.
And on top of that, AI controlled partisans knew to periodically pop up in key times (say, in Poland a few weeks after the start of the invasion of USSR) and that was to some extent a wack-a-mole too. But that is the problem of the AI programming, not the system itself. Yes, AI used it in a bad way, but just because AI is stupid it does not mean you have to dump the whole system out of the window. Marine and Paratrooper landings were also something that AI could not do right but you do not see that being dumped, do you? No, they FIXED the AI.
Instead of fixing the AI to use partisan mechanics better, they dumped it.
I have no problem with something that happened only once or twice not being represented in the game. Like Doolittle Raid. But partisan warfare I am talking about here was not just some thing that happened once or twice, nor was it "ragtag band". It was highly organized force lead by the best officers. And NOT because someone decided to gather up after the defeat but because it was a National Military Doctrine long before the war started. Both Soviets and Yugoslav prepared special units, gear, doctrines for that. It was not spontaneous thing at all. And it was a relevant thing throughout the war.
Say, what if it was not decided to give Yugoslavia to communist after the war? Royalist resistance was to make beachheads in Adriatic so in 1943 Allies would land there, not Italy. Allied landings would be much easier and most of the Eastern Europe would not fall to communism. This, even in game terms, has some value. Tell me, how are you gonna fight the active resistance without that system?
What is a player to do when his country gets overrun?
Free territories partisans held were actually pretty big and lasted longer than some countries. And free territory means a territory (province) held by your forces, without the enemy being there. How is that represented by an enemy garrison standing there lowering revolt?
I was not saying that current system is BAD, I am saying it LACKS a few things that previous games had. A few important things. Not important if you play with 4-5 big nations, important if you play with any of the other 100. And to make it all even more stupid, you can bet your ass that partisan mechanics WILL BE IMPLEMENTED as a DLC or expansion. Now, I had no problem with that in HOI3 because HOI2 did not have it. So they made it for HOI3, the game grew, they learned a few things... there is not a single excuse for it not to be included in a core HOI4. Except making more money. Again, no problem here (they do not make it because they do not have better things to do - they make it for money - a perfectly legitimate thing anyone would do), just do not justify it by other things that make no sense.