DISCLAIMER: There seems to be ongoing uncertainty about this, and other people have claimed that this is bugged and does not work as intended.
I believe the "book line" so to speak is that each command level in a hierarchy provides 25% of its bonuses to the formations directly beneath it, and this 25% multiplication happens at each level of the hierarchy, i.e. if you have Brigade --> Regiment --> Battalion then each battalion only gains 6.25% of any benefits from the brigade commander.
Assuming there are no bugs, the net effect here is that it only makes sense to place commanders in charge of "empty" HQs if the number of immediate subordinate formations is greater than or equal to 4. However, even with this consideration there is really no reason to have bare or empty (HQ-only) formations as you can gain a greater benefit from the commander by placing actual units in their formation. For example, consider two hierarchies with identical total forces:
(1) Four battalions under an empty regimental HQ
Regimental HQ - 20k ton capacity, HQ only, 100 ton size
Infantry Battalion - 5k tons
Infantry Battalion - 5k tons
Armor Battalion - 5k tons
Artillery Battalion - 4,900 tons
In this case, the regiment commander gives 25% of his bonuses to four battalions for a net 100% bonus. That sounds good, however we can do better.
(2) Three battalions under a regimental HQ with support elements
Regimental HQ - 20k ton capacity, 100 ton HQ + 4,900 tons of artillery
Infantry Battalion - 5k tons
Infantry Battalion - 5k tons
Armor Battalion - 5k tons
In this case, since there are only three subordinate battalions the commander gives 25% of his bonuses to three units for a net 75%. However, in addition the artillery which is now directly under a commander gets a full 100% of the regimental commander's bonus, thus the grand total is 175% bonus which is much better than the above.
(One might ask why we do not use a larger 20k ton formation so that all of the units benefit from the regimental commander. Of course, the answer is that each battalion is benefiting from their own commander as well.)
Which means the most effective O/B would be the following
A single T9 HQ (full size of army)
->Supply Truck Formation(s)
->A single T8 HQ (Army size - supply size)
->->A single T7 HQ (Army size - supply size)
->->->A single T6 HQ (Army size - supply size)
->->->->A single T5 HQ (Army size - supply size)
->->->->->A single T4 HQ (Army size - supply size)
->->->->->->A single T3 HQ (Army size - supply size)
->->->->->->->A single T2 HQ with all med size AA guns(Army size - supply size)
->->->->->->->->Multiple T1 HQs (this is where ALL of the troops are)
So the O/B is less of a tree, and just a long line, only branching once you get to T1. It doesn't seem like any of the commanders effects do anything to supply trucks so they don't need any HQs. (logistical ability checks the unit firing not the supply truck if my understanding is correct)
Please someone tell me im wrong about this,
There are a few problems with this structure.
- First, there are indeed diminishing returns as mentioned.
- Second, if you are using auto-promotions then you may not have sufficient high-ranking generals to command a formation higher than T5 or T6, since every formation requires a commander who outranks any commanders of subordinate formations. Related to this, you will waste a number of leaders and/or HQ tiers - if your T2 commander is rank 2, then only rank-1 commanders can command the combat troops and rank 2+ leaders will compete for a single job at each rank; on the other hand, if you allow commanders of any rank below your highest to control T1 formations, then your highest-ranked commander will be at T2 and the higher commands will be useless. Finally, by placing a single commander (at each tier) above all formations you lose the ability to specialize - you could for example gain more benefits from grouping armor formations under commanders with high offensive and maneuver ratings, grouping infantry formations under skilled defensive commanders, and so on.
- Finally, the last major problem with this HQ structure is research and build costs, which both increase linearly with the HQ command size with no upper limit. For example, if you have 50 battalions of 5,000 tons each, the HQ to control them all must have capacity 250,000 tons which will take 5,000 RP to research and 100 BP to build for each level of HQ (more if you want to armor them for added protection). For a single unit this isn't prohibitive, but you will have to continually re-make your HQ every time your forces increase in size to keep command over all units. Frankly, not only is it prohibitively expensive to research and build a HQ that can command your entire ground army, it's unnecessary - most people only build their OOBs with 2-4 levels/tiers unless they are RPing heavily and do not have a top-level command that controls all units. If for example you have HQs for 5,000, 20,000, and 75,000-ton command ranks, not only are these cheaper to research and build but the higher-level HQs which usually stay in the rear areas will rarely need to be upgraded since they do not have to grow as your army grows (smaller front-line HQs should still be upgraded for survivability of course).
