Please give me some tips on building and using ground troops

[nuclearslurpee]

~snip~
I feel obliged to point out that this misunderstands how breakthroughs work, as a breakthrough does not give the defenders an extra round of fire - only the attackers. As such, any frontline component in a support-echelon element is completely useless as they will not even fire in self-defense against a breakthrough.
~snip~

 --- Yeah, no it seems that's totally how it works. Huh, that's kinda crap as it means there is literally no reason to defend anything in the Support / Rear Echelon positions. At least not organically that is. That's a bit dumb in my opinion, although not terribly unlike real life I suppose. Then again... rear Fire Bases, HQs and the lot do tend to be rather well defended on the whole.

Yeah it is definitely a sad limitation of the ground combat mechanics as they exist. It would be nice if it ever got fixed but I don't expect this as it would mean a serious rework in what I'm sure are messy bits of the code.

[Lord Solar]

Here is my design tactic which has worked time and time again against NPR forces for attacking fortified NPR planets.

The basic unit I use is Super-Heavy Vehicles with Super-Heavy Vehicle armor, and triple CAP. You can use HCAP if you are out-teched a bit or want better performance against enemy vehicles, but this is to grind through infantry so I find CAP better. I usually start producing this around Ion tech.
I organize these units in formations of 5k-25k tons and generally set them to front line attack with the best Ground Combat Offensive commander I have.
These units will kill x10 their tonnage in enemy infantry in an invasion easy and will grind through enemy armor eventually. They will suffer few losses at most unless you are really outteched.

For more specialized units, consider maybe 10% of assault forces mounting MAV, HAV (if outteched), or HAC (if you outtech them) to more effectively deal with enemy vehicles. You will want this on enemy worlds with a lot of forces but don't need it all the time.

I also use Infantry in defense to protect logi armed with PW in defense, maybe some statics with anti-tank in there somewhere, and for logi I used Light Vehicles in rear formations. I often assign frontline units as subordinate to these formations to ensure resupply.

This sort of setup will allow you to completely destroy massively larger and more expensive NPR formations with few losses.

[Jorgen_CAB]

There are allot of different tactics and considerations depending if you are going up against the NPR or a another human controlled faction (as in multi-faction games).

I usually always build my armies as if I was fighting against a human opponent as it is too easy to game the system otherwise, but that is up to you to decide.

First of I like to build my line units in sizes of 15-20k generally as there is a limit to the amount of officers I will have at any given moment, I then have support forces as 5-10k in size or elite formation sometimes allot smaller, depending on what they are meant to perform. My 15-20k formations are lead by level 2 commanders and my supporting forces are led by level 1 commanders, this is the general rule.

Each 15-20k formation basically is roughly a battalion sized elements and can be considered the smallest formation that can operate on a semi strategic level on its own in Aurora. I usually imagine forces in this time-frame to have considerable fire-power in comparison with even the most effective modern forces. So they can cover relatively large areas and be quickly transported on a planetary surface from place to place. Each such formation uses its own strategic transport system of some kind.

Anyway... I usually have about three tiers of army which are garrison, regular army and the marines.

The garrison are mainly infantry and static formations but may also have a mobile reserve on more important planets or colonies with primarily light and some cheaper medium vehicles.

The regular army is a truly mechanised force with a balanced force and will be the vastly largest portion of the army in terms of cost. They are not going to have the most expensive units money can buy as they are expected to be used both as defensive and offensive forces but will have a considerably large portion of tanks for potential breakthrough and be useful both on offence and defence.

Marine forces are going to be deployed using the best possible armour, bonuses and weapons that is available. They also will be deployed with the best and most heavily armoured assault ships the state can afford. Cost here is not the issue but having as much firepower and staying power for the amount of tons you can cram into a ship is paramount.

Some typical units I use are...

IFV: Medium Vehicle, light armour with LAC, CAP
APC: Light Vehicle with CAP or LAC
MBT: Medium Vehicle, medium armour with MAC, HCAP or CAP
HBT: Heavy Vehicle, medium armour with MAC, HCAP

Medium and Light Bombardment units on Vehicle chassis usually go into front line formations while static units almost always are reserved for support/rear echelon with respective bombardment capabilities. Only Marine forces will get heavy armoured artillery pieces in heavy vehicle chassis for bombardment in support/rear echelon.

As I usually tend to favour Plasma Carronade for energy weapons these days I generally have my weapon tech for ground troops a few tech levels higher than armour, this is why I tend to favour the Auto-Cannon in favour of Anti-vehicle weapons and usually can employ lighter Anti-Vehicle weapons which still are quite effective at heavier vehicles, at least up to heavy vehicle chassis. I do employ specialised anti-tank vehicles too, but they usually go into specialised companies that often is held in reserve until they are needed.

One thing to note is that cheaper forces in terms of armour is more cost effective in Aurora, yet not space efficient. But if you mainly are invading planets after you suppressed their STO then you could usually build enough cheap troops transport which are more economically cheap in the long run than extremely expensive forces. So I tend to have a small number of very expensive marine forces for special operations and then a regular army for the major large scale planetary operation that don't operate from drop capable ships like the marines can.

A typical marine assault carrier has a full battalion of 20k troops and about 5k of support troops. They also have a large civilian hangar and enough maintenance to hold a decent amount of air-to ground assault crafts, enough to support the formation and do some air defence suppression. The 20k of marine troops and their carriers often are as expensive as almost a full division of regular troops. You can imagine they are not useful for large scale operation on their own but can obviously be part of them. A normal mechanised battalion is about 700 grunts and around 200 light to medium vehicles with a build cost around 1000 and the troops carrier to hold it (20k tons carry capacity) is about 650-750 BP depending on technology used, although once such a ship is built it is practically free in terms of maintenance cost.

[smoelf]

This is a really excellent thread with lots of good suggestions.

One thing I might add is to remain adaptable and flexible once you start encountering hostile forces. All of this is good to get your army going, but you will probably need to alter it along the way for the concrete situations. I have experienced this in two ways.

The first was when I tried my first planetary assault. I got my ass kicked, but that was probably mostly due to using too few troops, so I started rebuilding the army to prepare for the second attempt. However, another thing I noticed was that the planet actually had a terrain other than barren. It was an ice desert. Now, ice deserts to not provide a targeting malus to your own troops, so all I had to deal with was the targeting penalty from forticiation, but that is still a lot. So I decided to design and build a selection of troops with desert and extreme temperatures specialization to increase their hit chance. This took up, perhaps, a quarter of the new army, and had increased CAP after I had gathered some actual intel during the first assault. These then became my 'Arctic Regiment'. I still use them for other assault, since I have them, but they were designed for a particular situation.

The second was after a successful assault, but one which lasted far longer than I wanted. Going through the intel, I could see that their troops had better weapons tech than me, so even if I hit a lot of troops, the kill rate was crazy low. For several reasons I have gotten behind on weapons tech and do not see myself catching up any time soon, so instead I have designed a new formation for the next planetary assault. These consist mostly of LAC and MAC, which have greater damage and penetration than CAP/HCAP and more shots than MAV, so hopefully they can get a few more kills against a technologically superior enemy. Still, this is only a supplement, so a single formation of 5.000 tons per 125.000 tons division.

Finally, I would add some of my own designs, which are rather different. Mechanically they fit into the templates others have said, so this is just to give yet another example of how a thematic approach to your empire can show itself in ground unit design.

My current empire is based out of a jungle mountain planet and they have taken their close connection to nature with them into outer space. In addition to the basic infantry unit (Hunters; PW) most formations are also accompanied by a species of canines native to Aldor. These Plasma Hounds (INF; PWL) are ferocious and a formidable force. Fortunately, they also breed fast, which makes them ideal for filling up the ranks. I mostly use these as cannon fodder. They don't really kill anything, but PWL take very little space so they can soak up A LOT of shots - even if they also die quickly to them.

From the deepest mountains in the dark caves, the Spiked Worm resides (VEH; CAP/MAV). These have been tamed and trained to form the backbone of the main raid parties, flanked by plasma hounds to distract incoming fire. In the far northern reaches, their cousin lives in the arboreal. The Frost Wyrm (HVH; HAV/HAV) is a major destructive force, but also rather slow. Infantry units can easily evade them, so their taskmasters train them to destroy tanks and other mechanized forces.

From the sky, the mighty Roc rains down upon the hostiles in swooping attacks. These are modelled using ground support fighters with auto-cannon and bombardment pods, but thematically they are large, winged creatures.

[serger]

It is "cleaner" because supporting ground units means the fleet fires fewer shots to do the same damage compared to general orbital bombardment.

Aw, you mean cleaner compared to orbital bombardment, not compared to artillery fire.
Well, that's all too dirty for me to use widely, because the cause to mess with ground warfare instead of "glass and forget" option is to keep loot and civilian's lives, not to spoil it.

That's why my overall structure of ground forces is a bit lighter compared to what most players seems to use:
1. I don't use major ground forces defensively. If my Navy and Orbital defences so screwed up to let enemy land enough forces to beat planetary garrison - it means that this planet is already nearly operationally useless even if I'll hold there, so I'll likely surrender it and take my chances to reconquer it later, not trying to prolongate an agony. So my ground garrisons are just security forces, they have no bombardment units at all.
2. My major ground forces are also relatively light-armed. That is - no heavy artillery, minimal numbers of lighter artillery, and in addition - even heavy anti-armour units will move to the front later (not because of supply issue in the first place, but to not deal more collateral damage than it's necessary). They are, howewer, usually heavily armoured: I'm ready to pay more just to save more. So, my main GF usually is more like most players' Marines.
3. What is usually called Marine Corps or smth like this - it's in my games usually more like Special Operations squads: the best in terms of equipment and training, yet lightly armed and exclusively infantry, they are intended to capture ships and stations, not to assault any garrisoned planet.

That's probably not the best strategy mechanically (especially since I use FFD, AA and higher HQs just to make it look more complex and realistically - because that's what is to play), yet it's what I still can play, when I'm sick with news.