The 3 unit limitation

[Valkyrion]

Having skipped most of 8th-10th (I dipped my toes in 9th waters) I presume this came in for a reason? (and is why things like Land Speeders or battle tanks don't come in units of 1-3 like some of them did before).

 

Was there a main culprit? Did someone field 2000 points of hive tyrants or something?

 

 

 

[jaxom]

5 hours ago, Valkyrion said:

Having skipped most of 8th-10th (I dipped my toes in 9th waters) I presume this came in for a reason? (and is why things like Land Speeders or battle tanks don't come in units of 1-3 like some of them did before).

 

Was there a main culprit? Did someone field 2000 points of hive tyrants or something?

It was, supposedly, about opening up army composition to let players play with their toys. Eighth and ninth editions had a lot of interesting, but half-baked, design features along that line. The rule of 3 in ninth edition replaced the traditional detachment and it's 8th edition variants which had different slot allocations. It is part of why many vehicles no longer come in squadrons. The other part is splitting vehicle configurations into more than one datasheet. Battleline units were the "common core" of a faction and variants like Deathwing Terminators allowed factions to field their traditional armies (to an extend, and only for some factions).

[Tawnis]

Yeah, that's mostly the case, though it's not technically the rule of 3, that's only for 2k games. At 1k, it's the rule of 2, and at 3k, the rule of 4. 

But yes, it was essentially to stop people from spamming all of the current best unit in their codex. 

[Valkyrion]

Thanks for the replies, but I was kinda fishing for the actual spamming that ended up being too disagreeable, even for GW, if there was one. 

Was there a singular thing that was spammed so much, did well at tournaments and so on that directly forced this change? 

If not then it's just a balance patch from GW?

 

[DemonGSides]

I don't think it was any one list that caused them to flop into no force org. The detachments at the time were basically being used to just abuse the way into getting as many of the strongest datasheets as possible, devolving into things such as 7 Storm Ravens, or things like the Loyal 32, which was a way to abuse IG allies to increase the resources needed to play strategems.

 

Then detachments started getting looser while giving fewer benefits, and then Arks of Omen introduced The Rule of 3 towards the end of 9th Ed and it's been that way ever since, if I remember correctly (I am willing to entertain my brain has become mush and mixed up some timing).

[Dr_Ruminahui]

I think your recollection is correct, DemonGSides.

 

To put it into context, "detachments" (as in structural organizational limitations", however named) have been a things since way back to 3rd edition (and maybe prior, but I'm unfamiliar with those rules).  Basically, back then there was real friction between taking units because they were good and taking "a proper army" with a lot of basic troops. 

 

So, from 3rd to 7th (I think), the rules were written in a way to encourage this "proper" type of army construction, and broke units into different force organization types - so Troops (what are battleline today) with 2 mandatory and 4 additional optional slots (so, 2-6), HQ (so characters) with 1 mandatory and 1 optional (so, 1-2), and then three optional categories - Elites (so, non-battleline infantry), Fast Attack (fast stuff, like bikes, jump infantry and speeders), and Heavy Support (basically everything else that wasn't a dedicated transport) - all of which were 0-3 for each category.  And dedicated transports, the exact ratios for which I don't remember.  

 

So, while there weren't hard limits on any particular unit, there was for each category, essentially creating a limit of 3 for any given unit, or 6 for troops.  Which is probably where those numbers  today come from.

 

Now, as editions progressed, it became clear that this rigid structure, while being "proper" for many armies, excluded many army classic archetypes, and GW began to tweak it.  One of the first instances was the 2nd 3rd ed. chaos codex, where certain legions tweaked the limits (iron warriors got +1 Heavy Support for -1 Fast Attack, and Night Lords vice versa).  Another was Imperial Guard (what is now Astra Militarum), which was the first codex (to my recollection) that let you get multiple units for one slot - you could get up to 6 infantry squads for one Troops slot, I think.  Eventually (and I think this was in 4th) this was opened up even more for Imperial Guard Armoured company, which was the first (I think) that let you take up to 3 tanks in one slot, essentially creating what is now the vehicle squadron for things what weren't light walkers (as I think IG sentinels and ork killa kans were already 1-3 unit - and there may have been some other light non-walkers that worked this way, like ork buggies/wartracks).

 

Then, as discussed by DemonGSides, in 8th GW created a more complicated detachment system, where a player could essentially chose more than one OG style detachment, with different types with different unit limits (so, there was a Fast Attack one with multiple FA slots + an HQ, a heavy one, and elite one, etc).  Given that the way these worked didn't require everything to come from one codex, this allowed quite a bit of diversity in force creation, especially for imperial forces.  As this could allow for potent combinations and/or the ability to "cherry pick" the most efficient units from various codexes and create a force that some felt wasn't representative of how an actual army should look like, this attracted the pejorative term "soup" / "souping".  In 9th, this became even more controversial as the game benefit of doing so increased - where in addition to picking the best units, taking multiple detachments was the way you got more CP.

 

Another issue that came up was the spamming of units - throughout this process, the game retained the "squadron" system established in past editions to allow players to field multiple vehicles for a vehicle heavy force.  This allowed players to "spam" the most efficient choice.  Given the way the detachment system worked in that one could always take more detachments (usually with just the tax of needing to take a character), it no longer worked to limit how many of any particular unit a player could take.  Recognizing that some players didn't find it fun to play against an army composed only of the 1 best unit and some assorted HQs from an army, GW (re)introduced such limitations, though this time on how many of a given datasheet one could take.  I seem to recall Chaos Wardogs and Ork Buggy lists being 2 lists that got moaned about a fair bit in this context, but I can't say to what extent these actually triggered this change.

 

So, looked at historically, in my view the unit caps don't seem to be a change "required" by any particularly potent army composition, but instead arise from the tension between letting players play what they want to play (even if, or because, its overpowered) and the combination of wanting players to make armies compositions that matched what were presented as typical in the fluff and many players preferring to play against (or play, and not feel like they are being punished for doing so) more diverse and/or representative armies. 

 

I have a fair bit a sympathy for both sides on this, and feel that there is no "right" answer, just a balance- and to me, the "3 unit" limitation is a workable compromise.

Edited Monday at 10:05 PM by Dr_Ruminahui

[Griefbringer]

On 10/5/2026 at 9:17 PM, Dr_Ruminahui said:

To put it into context, "detachments" (as in structural organizational limitations", however named) have been a things since way back to 3rd edition (and maybe prior, but I'm unfamiliar with those rules).  Basically, back then there was real friction between taking units because they were good and taking "a proper army" with a lot of basic troops. 

 

As for the pre-3rd edition army composition systems, the original 1st edition (RT) army lists did not have any common structure. Rather, the types of limitations varied from list to list, some being very freeform, others being stricter with minimum or maximum caps for some of the units. The Imperial Guard list was highly restrictive on multiple levels, and putting together an army and playing it with that list in point match games might have required a special level of masochism.

 

2nd edition army selection was based on percentage point limitations for various categories (similar structure can be seen e.g. with Warhammer: The Old World lists). Typical limitations were:

 

- 0-50 % of Characters

- 25-100 % of Squads

- 0-50 % of Support (vehicles, dreadnought, artillery, allies)

 

Additionally, the lists had 1 compulsory character choice (for commander), and in most forces this was fixed, so the Space Marines usually needed to take an expensive captain to lead even the smallest strike force, which could feel odd in small games (later WD article suggested adjusting this for Space Marines so that any other character could be used as a substitute in small games). There were maximum limits for some units (e.g. 0-1 for Blood Angel death company), but otherwise the lists were quite freeform - you could spam most squad types as much as you wanted.

 

Imperial Guard had additional level of limitations (on top of the percentages), where for each command squad you could take up to three regimental squads (infantry or heavy weapon squads), and for each regimental squad you could take one additional squad (ogryns, ratlings, storm troopers, sentinel squadron, tank). Additionally, most squads could also take a chimera, so you could easily build a fully mechanised list.

 

3rd edition force organisation chart (FoC) was already discussed previously quite well, but the designers of the time described it as a means to put some limitation and structure to the forces (which under 2nd edition could be rather character heavy), as well as trying to provide some guideline as to what the typical forces of the 41st millennium could be expected to look like. Some armies ended up fitting the structure quite well, while others could have rather limited options for some of the slots.

 

Interesting feature of the FoC system is that it could easily allow you to field a whole Space Marine battle company (captain with command squad, chaplain, 6 tactical squads, 2 assault squads, 2 devastator squads, Rhinos as dedicated transports) with some reinforcements (e.g. terminator squad, dreadnought, land speeder squadron, predator). Considering that the space marines were the iconic force of the setting, this may not have been accidental.

 

You would need to play quite a big game to have enough points to field the whole battle company, though. On the other hand, for the really big games there was option to field multiple FoCs for each side, though depending on army you could be expected to fit 2000-3000 points of units to single FoC before running out of slots. And if you and your opponent agreed to use the titans and super-heavy vehicles from Forge World, those would be outside the ordinary FoC limits.

 

As for the Imperial Guard platoon rules, which allowed for taking multiple units in a single slot (which sometimes confused new players), this existed in the 3rd edition rulebook army list for the basic Infantry Platoon, and was later expanded to Command Platoon (initial 3rd edition codex) and Heavy Weapon Platoon (second 3rd edition codex). There were also two different variants of the Armoured Company list published in WD during 3rd edition in issues 253 and 296; the first of these allowed for taking a tank squadron (1-3 vehicles as a single unit) in a single slot, while the second one limited tanks to one per FoC slot.

[Griefbringer]

On 10/5/2026 at 9:17 PM, Dr_Ruminahui said:

And dedicated transports, the exact ratios for which I don't remember.  

 

Some more (rather trivial) commentary on the 3rd to 7th  edition Force Organisation Chart (FoC) from me.

 

Dedicated transports did not have specific slots on the FoC. Instead, various infantry units (depending on the army list) had a choice to buy a dedicated transport to accompany it, and this would be part of the same FoC slot as the parent infantry unit (but was a separate unit for game purposes). Armies with good access to dedicated transports could be able to field 9-14 such vehicles if they had the points to spare. In the 3rd edition army lists, some units (e.g. Tau Pathfinders) had compulsory rather than optional dedicated transport choices, though there cases were rarer back then and even rarer in later versions that tried to make the army composition simpler and less restrictive.

 

In principle, various versions of the Imperial Guard mechanised army list would have been able to fit ridiculous amounts of infantry squads in Chimeras into a single FoC entry, though in practice the point cost of such units would limit the number that could be actually fielded in a 1500-2000 point list.

 

On 10/5/2026 at 9:17 PM, Dr_Ruminahui said:

vehicle squadron for things what weren't light walkers (as I think IG sentinels and ork killa kans were already 1-3 unit - and there may have been some other light non-walkers that worked this way, like ork buggies/wartracks).

 

There were quite a lot of armies in 3rd edition that had access to light vehicle squadrons of 1-3 vehicles in the 3rd edition. At least the following:

 

- Eldar: Vypers, War walkers

- Orks: Killa kans, Warbuggies/traks, Guntrukks (Speed freeks), Deth koptas (speed freeks)

- Space marines: Land speeders

- Imperial guard: Sentinels

- Witch hunters: Penitent engines

 

Tau were initially neglected in this respect, until the 4th edition Codex Tau Empire gave them Piranhas as fast attack choice - these could be exceptionally fielded in units of 1-5 vehicles (though 5 vehicle units may not have been a common sight in practice).

 

_____________________________________________________________________________________________________________________________________________________

 

Another variant on the "Rule of Three" in some 3rd/4th edition codices are some army list entries where you could buy three units of a given type in a single slot, but you could only buy a single slot of that type - thus still limiting you to maximum of three units of that type. These were most common in the Tyranid codex, which applied such limitation to Lictors, Zoanthropes and Biovores. Other cases include at least Daemonhosts in the Daemonhunters book and Sniper Drone Teams in 4th edition Tau Empire book.

 

4th edition Tau Empire book (2006) also had some additional limitations in terms of army composition, in terms of compulsory picks (1+ Commander as HQ, 1+ Fire Warrior unit as troops, Pathfinders having to take Devilfish transport for each squad). It may have been last codex to apply such limitations, with most books after that trying to make things simple and straighforward with the FoC use, avoiding any additional limitations.

[ValourousHeart]

There have been various limitations put on repeat units over the editions.

In second edition the armies were limited by percentages split between characters, core, and support.  Core might not be the right term, but it incorporated most of the infantry units for the army.  Support tended to be the tanks and transports.

 

From what I remember Sisters of Battle were the only codex that had an additional limitation that other armies didn't have.  You were limited to 1 seraphim unit for each battle sister unit your army included.  This was foreshadowing the FOC introduced in 3rd.

 

The Force Org Chart (FOC) was the 1 HQ and 2 Troops that most of us remember, and was the main system 3rd through 7th.  The basic FOC was 1-2 HQ, 2-6 Troops, 0-3 Elites, 0-3 Fast Attack, 0-3 Heavy Support.  Later editions made modifications to this format to give a little more flexibility in army construction.  

 

The slots in the chart were the limiting factor, not specifically a limit on repeat data sheets.  Especially considering that multiple formations / detachments were possible effectively lifting the slot limitation.

 

That was until a tournament in late 6th where a player did show up to a tournament with 6 hive tyrants.  The rule of three was introduce in the very next balance update, something like 4-6 weeks after that tournament.  Interpret that timing however you want.

 

A variation of the rule of 3 had been in the game ever since, often with an exception made for specific infantry units and dedicated transports.

 

Squadron was introduced in 3rd edition.  All the squadron units in the game either gained it at the start of 3rd  (land speeders, killa Kans, Sentinels, war walkers) or when they were introduced to the game (piranha, fire strike turrets).  Land speeders are the only unit that lost squadron.

[Griefbringer]

11 hours ago, ValourousHeart said:

Squadron was introduced in 3rd edition. 

 

Minor correction: squadron rules existed already in the 2nd edition, though they are not found in the main rulebook, but in the Dark Millennium rulebook. They would not affect how you purchased units, but before a game you might need to combine some of your vehicles into squadrons (which could contain a mixture of different types of vehicles). The vehicles in the squadron were limited to some extent from acting independently, though the rules were not particularly straightforward.

 

(Despite the British heritage of GW, the term squadron in WH40K setting has little to do with modern British Army usage, where it refers to a company-sized unit of armoured vehicles.)