Here's my problem.
The British Army never had more than 114 Regiments (thats from memory the highpoint in 1808). Most regiments had just one battalion at that time. So there was no need to refer to anything other that the regimental number. Post Cardwell reforms there was usually a 1st and 2nd battalion that were regulars and a 3rd, 4th, and 5th Militia battalions.
The US system assigns a number from a series to the HQ unit according to when it was raised. To apply that to the OTU you need someone to assign series. It just strikes me as making it difficult to foster a sense of heritage
their were regimental numbers up to 135th regiment, although the highest numbers often existed only for a few months while recruiting, then were disbanded and the troops were used to backfill other, understrength regiments. the higher numbers were often created and disbanded several times (their were no less than 6 different units called the "96th" regiment, for example).
while a lot were one battalion, plenty were not. the 60th (Royal American) regiment had no less then 7 battalions during the Napoleonic wars. Since the battalions very rarely served together, the convention was to refer to a battalion by the regimental number (so both 1st/60th and 2nd/60th would be called "the 60th regiment of foot"), at least on the field. orders and reports generally listed the battalion number as well (so the generals report would call them "2nd battalion, 60th foot")
as for the "hard to fight for a number" thing, Tommy Atkins fought just as hard for the 33rd regiment of foot as he did for Huntingdon's Regiment, the Yorkshire West Riding regiment, the Duke of Wellingtons Regiment, or 3rd Battalion, The Yorkshire Regiment. (for those who aren't experts on the history of British regiments, that is the same regiment under different naming conventions.)
.
From T5 and canon sources there are battalion numbers in the form XXX and Brigade numbers in the form YYYY.
So if you only have 999 battalions that works, and if you have 9999 Brigades that works. But if you do actually have 9999 Brigades that could mean you have around 3996 battalions or more. How does that work? Even if the IA is small its not an elegant or memorable system.
I think its even noted in the MT Rebellion Sourcebook that numbers are duplicated across the Imperium. That is a recipe for disaster when you're trying to track units and route logistics.
see, the romans had something like 6 legio I, 5 Legio II, and 5 legio III, most of them active at the same time. but they managed to make it work.
plus, just because we only have evidence for a 3 figure battalion number does not mean that their is less than 1000 battalions, just that their is a battalion with a 3 figure number. the 365th could well be 3rd battalion, 6th brigade, 5th division, as you talk about below.
I can see how your solutions would work but:
1). In solution one you may end up with regiments with many battalions widely separated by distance and culture. and huge inter battalion rivalry or feuds.
2). In solution two your limiting the numbers available to a territory. What happens when you need to raise more battalions than you have numbers for?
1) well, inter battalion rivalry is endemic in commonwealth nations, is a side effect of promoting the battalion and regiment as the focus of loyalty.
2) then assign another number block, or borrow numbers form another block. unless your raising hundreds of regiments at once, it's unlikely you'd use up the entire address space in a short time. and if you do, then you could just start raising extra battalions for existing units (some regiments had 30 or more battalions during the world wars)
Giving a planetary name to a regiment is purely IMTU because I like the idea of each regiment having its own culture, heritage and quirks that tie it both to the planet and the Imperium.
And just to expand on the system I use when we assign a battalion like the 2nd Battalion 50th PlanetName Regiment to a brigade it either goes to an Independent Brigade or a Divisional Brigade in the SectorName Command.
Independent Brigades are numbered from 1 to 9. So you may have the 7th SectorName Independent Brigade.
Divisions are numbered as 1st, 2nd, 3rd etc. and the brigade number is added. So the third brigade assigned to the 1st SectorName Division becomes the 13th sectorName Brigade.
Corps are numbered using Roman numerals eg. XX Corps.
oh, I'm british army myself, so I totally dig the preference to have the 2nd/50th (Ball of Dirt) regiment.
historically, I know the soviets used Independent Tank Brigades as part of their infantry armies (they were "Independent Brigades" in the sense they were not subordinate to a division).
?
