Dude, I want to say how valuable your feedback has been. You always take the time to offer a lot of incredibly in-depth advice, and it really helps a lot.
Any time mate
I don't know where I got the idea, but I thought it was usually best to keep all infantry and vehicles in one place. Not accurate?
This is understandably confusing since there's a couple different concepts of "place" in Aurora ground combat. On one hand you have the front line (versus support/rear) and this is where you want specific weapons (CAP/AC/AV) which are often most effective when mounted on vehicles, and in this case it often makes a lot of sense to support them with infantry for the meatshield effect - if you put 100 tanks on the front line MAV will eat them alive, but if you put 50 tanks and 500 infantry on the front line a lot of MAV shots will be wasted to kill a single rifleman instead. On the other hand there's the question of formation organization which you can do in many different ways. Some people will mix their vehicles and infantry in a single formation, other people will have separate formations of each and attack with a mix of both formations. As long as you end up with a good mix of weapons on your front line it doesn't matter that much how they're organized.
Related, but what's a breakthrough formation? I haven't had the chance to actually participate in the new ground combat yet (haven't gotten there in my current run), so it may be something obvious I just haven't experienced yet.
If an attacking formation destroys or routs a defending formation, it can conduct a second attack during the same combat phase, often against a formation in the enemy support or rear echelon. While it's a hazy concept in Aurora as any unit except STA can effect a breakthrough, in general the units most likely to cause a breakthrough are heavy attacking formations with a lot of killing power, think a tank battalion as opposed to a light infantry INF-PWL battalion.
I was a little fuzzy about the relationship between logistics/construction units helping other formations. From the notes, it looked like formations would only draw on the supplies and construction assets of their superiors, meaning that a battalion wouldn't look for help from another battalion. That restricted me a bit, side it meant I had to put all my CON/LOG in the HQ formation. Was I mistaken?
I somehow had the impression that a LVH-LOG element could resupply any unit in its parent HQ's subordinate hierarchy, which seems to be incorrect - that's my mistake. In that case, just put the supply trucks into your HQ formation and roll with a 2,000-ton HQ formation (I always do this, anyways, to reduce micro). CON is not as restricted as LOG and can fortify any formation which is subordinate to its own parent HQ (I got this confused with LOG here), which allows you to have separate CON formations for non-combat operations that can be attached to a superior HQ for the purpose of fortifying a defensive army. That said, there's no reason you can't or shouldn't put them into your superior HQ for defensive units, but since CON doesn't help you on the offensive it's not needed for an attacking formation/HQ.
Lastly: were my ideas about what was wrong and how to fix it accurate? Did I understand static units correctly?
Static units like vehicles can be Anything You Want™ as the only real mechanical effects of the STA unit type are inability to break through and potentially having higher armor compared to INF unit types with the same fortification limit. I've seen people argue that a large artillery gun (MB or HB) should be modeled as STA since those are fairly immobile unless they are mounted on a vehicle, for example. In terms of game mechanics, STA are usually better that vehicles to mount heavy weapons in defensive formations since they get a higher fortification bonus, while vehicles are usually better in offensive formations even for artillery (a VEH or HVH with 2x MB can have higher base armor than a STA, which helps in the absence of a fortification bonus).
ADDENDA:
Excellent; this is great stuff!
I was wondering, though: you guys have sold me on the usefulness of deep command structures, but I'm not sure how that would work in practice. The problem for me is redundancy vs specialization.
Real command structures get more and more specialized assets the higher you go (rifles, to tanks, to aircraft, etc). I think I can see specialization in a few layers: guns or armor at the bottom, both one layer up, artillery the layer after that, and STOs after that. That makes four layers: infantry/armor battalions, regiments with access to both, brigades with an added artillery battalion, and divisions with an added STO battalion. Maybe corps with xenoarchaeology, construction, and survey battalions added on.
... Actually, now that I've written that out, that seems like a decent idea. Fairly modular, too: you can add, remove, or swap out battalions for others depending on the needs of the situation and the transportation restrictions. For example, a garrison regiment might swap out the armored battalion for a construction one to take advantage of fortifications (assuming that a battalion can fortify another battalion, which I'm not sure about).
How's that sound?
Generally, it helps to define a planned structure for your HQ hierarchy and then build to that specification (which can change over time due to experience, game situation, etc.). For example, a common structure would be to use Battalions (5,000 tons) as the base formation, then Brigade HQs of 25,000 tons which control 5,000 tons of HQ assets (LOG, CON, AA, HQ) and up to four subordinate battalions. Then define Corps HQs of 100,000 ton capability which would control 2 or 3 brigades and several additional battalions which could be more specialized or just used as reserves. Each HQ formation itself has the same 5,000 ton size in this example.
For example, a planetary offensive corps could be built like:
Planetary Offensive Corps: HQ100 + LOG, AA
Armored Brigade: HQ25 + LOG, AA, FFD
3x Armored Battalion (5,000 tons each)
1x Mechanized Artillery Battalion (5,000 tons)
Mechanized Infantry Brigade: HQ25 + LOG, AA, FFD
3x Mechanized Infantry Battalion (5,000 tons each)
1x Mechanized Artillery Battalion (5,000 tons)
Mechanized Infantry Brigade: HQ25 + LOG, AA, FFD
3x Mechanized Infantry Battalion (5,000 tons each)
1x Mechanized Artillery Battalion (5,000 tons)
2x Super-Heavy Armor Battalion (5,000 tons each)
2x Heavy Artillery Battalion (5,000 tons each)
This isn't a very deep hierarchy but it's modular, flexible, and not very micro-intensive.
You could also do something a little deeper that represents a divisional type of structure. This has the advantage, if you think of it this way, of matching the 3:1 ratio between successive ground commander ranks if you use auto-promotions.
Armored Corps: HQ200 + LOG, AA
Armored Division: HQ65 + LOG, AA, HB, FFD
Armored Regiment: HQ20 + LOG, AA, MB
3x Armored Battalion (5,000 tons each)
Armored Regiment: HQ20 + LOG, AA, MB
3x Armored Battalion (5,000 tons each)
Mechanized Infantry Regiment: HQ20 + LOG, AA, MB
3x Mechanized Infantry Battalion (5,000 tons each)
Armored Division: HQ65 + LOG, AA, HB, FFD
Armored Regiment: HQ20 + LOG, AA, MB
3x Armored Battalion (5,000 tons each)
Armored Regiment: HQ20 + LOG, AA, MB
3x Armored Battalion (5,000 tons each)
Mechanized Infantry Regiment: HQ20 + LOG, AA, MB
3x Mechanized Infantry Battalion (5,000 tons each)
Mechanized Infantry Division: HQ65 + LOG, AA, HB, FFD
Mechanized Infantry Regiment: HQ20 + LOG, AA, MB
3x Mechanized Infantry Battalion (5,000 tons each)
Mechanized Infantry Regiment: HQ20 + LOG, AA, MB
3x Mechanized Infantry Battalion (5,000 tons each)
Mechanized Infantry Regiment: HQ20 + LOG, AA, MB
3x Mechanized Infantry Battalion (5,000 tons each)
Lots of possibilities. Point is, if you design a HQ structure first, then design divisions to fit, it's probably easier to get it working. However you can always design for modularity so that it's possible to swap individual battalions or entire subordinate hierarchies in and out to fit a specific mission profile.