Military Forces and Spending in Classic Traveller

(v1.0, 6 September 2005)

I have taken a bottom-to-subsector look at the ground and naval forces depicted in classic Traveller. To the extent that my assumptions are valid, I conclude that the military forces and spending levels depicted in classic Traveller are reasonable and internally consistent across a wide variety of references and citations -- rules, games, articles, JTAS news entries, etc.


Up front, I will assume that -- for the most part -- GDW knew what they were talking about, particularly concerning military matters (after all, they were a wargame company first). Further, I will assume that all sources of information on the OTU (e.g., books, supplements, games, JTAS articles by GDW staffers) were intended by GDW to represent the same reality, and are equally valid unless proven otherwise.

For the purposes of this analysis, I will ignore the effect of populations modifiers. These did not appear in print until Alien Module 3 (1984, after most of the sources used here), and even then were only indifferently applied. My intent is to arrive at a consistent picture of naval forces as portrayed in canon when it was written; whether these should be multiplied by 5 (canonical average population modifier) in the final step is a subject for further debate.


I have done the analysis for any rule which gives statistical results, using the rule as written. The ranges I report do not include very low probability tails (< 0.05%) at either end, which may skew the averages slightly (although with only ~280 sample subsectors in the Imperium, it should not matter). [Another approach someone might like to try is to automate the rules I reference, run off a few hundred thousand sample systems, and do an empirical analysis of the results.]

Figures for which I could not get an exact rule or supportable average value are normally given maximum and minimum figures, and an assumed "best guess" median value. The end results are also expressed as a range of possible (best/worst case) values and an estimated median.

I have been careful not to rely too heavily on single examples from canon, which may not be typical. Where possible, I have tried to confirm the validity of the citations I use by comparison to similar, but perhaps not directly applicable, cases (e.g., checking the equipment of the 4518th LIR and Imperial Marine Task Force against their Zhodani and Sword Worlds counterparts). In most cases, I have not noted these comparisons: I have simply avoided using figures I could not confirm this way.

Finally, note that the published canonical sectors are in some respects not typical of the rules as written: for example, both the Spinward Marches and the Solomani Rim use Scattered (1/3) stellar density, rather than the Standard (1/2) used here.

Naval Forces


Escorts: up to 5000 tons (Supp. 9, pp. 9-10).

Auxiliaries: Size is variable, although 10,000 and 20,000 ton bulk carriers were in use in the Spinward Marches as of 1105 (Supp. 9, p. 25).

SDB's: 100+ dtons; examples range from 200 to 50,000 dtons (Supp. 7, pp. 35-38, 47; Supp. 9, pp. 25, 44-45; Adv. 6, pp. 38-39; Adv. 7, p. 37). Average size ranges from 400 dtons to a maximum of about 10,000 dtons(1); assume median 2,000 dtons.

Cruisers: 20,000 to 100,000 tons (Supp. 9, pp. 9-10); examples (Supp. 9, pp. 28-33; Adv. 5, pp. 21-22) range from 30,000 to 75,000 dtons.

Battleships: Assume larger than cruisers (100,000 to 1 million dtons); examples (Supp. 9, pp. 38-43) range from 200,000 to 500,000 dtons.

Battleriders: 10,000 dtons or more (Book 5, p. 19); 50,000 to 100,000-ton range (JTAS #9, p. 43); examples range from 20,000 (SMC, p. 35) to 50,000 dtons (Supp. 9, pp. 44-45).

Fleet Tenders/Transports: 200,000 dtons (Book 5, p. 19) to 1 million dtons (Supp. 9, p. 44). Tenders carry roughly 50% of their tonnage in battleriders (Adv. 5, p. 17).


Squadrons normally consist of two to eight capital ships plus escorts and support ships, for a total of about 10 to 20. (Book 5, p. 19; Supp. 9, pp. 16, 38, 42; JTAS #9, p. 40; I:E, p. 2; SMC, pp. 32-33). Squadrons of 10 or more like-type ships are possible, but unusual and "oversized" (Supp. 9, p. 16).

Cruiser Squadrons: two to eight cruisers (20,000 to 100,000 dtons each), plus escorts and auxiliaries. These represent less than 25% of capital ship tonnage (Supp. 5, p. 3; JTAS #9, p. 40). Total tonnage: 50,000 to 1 million dtons. Examples (Supp. 5, p. 3) tend to lower numbers; assume median 4x 50,000-dton + 25% = 250,000 dtons.

Battleship Squadrons: two to eight battleships (100,000 to 1 million dtons each, plus escorts and auxiliaries (less than 25% of capital ship tonnage; JTAS #9, p. 40). Total tonnage: 250,000 to 10 million dtons. Examples (Supp. 9, pp. 38-43) tend to the maximum number; assume median 8x 200,000-dtons + 25% = 2 million dtons.

Battlerider Squadrons: one tender (200,000 to 1 million dtons) with two to eight battleriders, plus escorts and auxiliaries (less than 25% of capital ship tonnage; SMC, pp. 32-33). Total tonnage: 250,000 to 1.25 million dtons. Examples (Supp. 9, p. 45; SMC, p. 32-33) tend to the maximum number of mid-range tonnage riders; assume median (8x 50,000-dtons) * 2 + 25% = 1 million dtons.

Assault Squadrons: transportation for 600 battalions (FFW, p. 20); assuming 500 troops per battalion = 300,000 troops at 3.3 to 5 dtons per person (SMC, p. 40) and 25-37.5% cargo capacity (per Book 5, @ Jump-4). Total tonnage: 2.7 to 6.0 million dtons; assume median 4 million dtons.

Tanker Squadrons: Imperial TankRons refuel four squadrons or self-refuel (@ Jump-3; FFW, p. 10). This is equivalent to a Class A starport (ibid., p. 20), which holds 2 million dtons of LHyd (Adv. 5, p. 39). Estimate 6.7 million dtons, total tonnage. Assuming a 1 BatRon : 3 CruRon ratio (see below), the range is 540,000 to 17.3 million dtons.


Planetary Navies

CT gives no explicit rules for numbers of SDBs, although the presence of local naval forces is confirmed for most worlds with tech level 7+ and a population of at least one million (Supp. 3, p. 40). Since, however, the SDB [Squadron] table from Imperial Squadrons (p. 28) for T4 predicts SDB numbers in FFW exactly, I will use it:

TL   7     8     9     A
7    1     5    50    5C
8    1     5    50    5C
9    1    10    1C    1K
A    1    10    1C    1K
B    1    12   120   12C
C    1    12   120   12C
D    1    15   150   15C
E    1    15   150   15C
F    2    20    2C    2K

I infer that the "planetary navy" of worlds with populations in the single-digit millions consists of a squadron of fighters (or equivalent), and estimate their contribution at 1/10 SDB (40-1,000 dtons; median 200 dtons) each.

The average Imperial world (per Book 3) fields 42 SDBs (17,000 to 420,000 dtons; median 84,000 dtons).

Colonial Navies

Colonial navies consist of jump-capable squadrons raised, paid for, and controlled (in peacetime) by worlds with high enough tech levels and populations (Book 5, pp. 1-2; JTAS #9, p. 40). There are 16 named colonial squadrons on the Imperial side in FFW, belonging to 10 systems. The rule seems to be:

Pop	CruRon	BatRon	AsltRon
8	1
9	1	1
A	1	1	1

The only exception is Regina, which has two CruRons; this may be due to its role as a subsector capital. The minimum is tech level A. Starport type and bases do not appear to matter. Assuming these parameters are typical, a subsector produces:

Worlds with colonial squadrons (TL A+):

# / Pop	A	9	8
0	0.456	0.378	0.521
1	0.360	0.370	0.340
2	0.140	0.179	0.109
3	0.036	0.057	0.023
4	0.007	0.013	0.004
5	0.001	0.002	
Average	0.781	0.966	0.648

Squadrons per subsector:

Sqdns	Cruiser	Battle	Assault
0	0.090	0.172	0.456
1	0.218	0.305	0.360
2	0.262	0.268	0.140
3	0.210	0.156	0.036
4	0.125	0.067	0.007
5	0.059	0.023	0.001
6	0.023	0.006	
7	0.008	0.001	
8	0.002		
Average	2.38	1.74	0.781

With one additional cruiser squadron for the subsector capital, the average is just under six (5.9) squadrons per subsector. Average total tonnage ranges from 2.7 to 25 million; median 7.4 million dtons.

Imperial Navy

At the start of FFW ("Imperial Order of Battle Chart"), Imperial naval squadrons number close to half their colonical counterparts, or one third of the total: 2:4 BatRon, 6:11 CruRon, 1:1 AsltRon, 9:16 overall. If so, Imperial Navy forces amount to roughly three squadrons per subsector. I will assume that the FFW initial forces ratio of 2 BatRon : 6 CruRon : 1 AsltRon holds, and that there is an even mix of battleship- and battlerider-type BatRons. The resulting range is 2.4 to 10.4 million dtons per subsector (median 4.6 million dtons).

One "fleet" headquarters (including independent task forces, etc.) is available in FFW for every 6-7 squadrons overall; this ratio holds throughout the game. This implies roughly three fleet headquarters per two subsectors, or one per two regular Imperial Navy squadrons. These belong to the Imperial Navy, but control both regular Imperial and Imperialized colonial forces in wartime (JTAS #9, p. 42).


All worlds with local planetary and colonial naval forces have their own bases to support them (Supp. 3, p. 40). These are not depicted on the standard subsector maps.

Imperial naval bases (Supp. 9, pp. 6-7) exist in 17.4% of all systems (Book 3, p. 10); this means there are 2-14 per subsector (average 6.9). If large (multi-squadron/fleet) bases exist at all, most bases must be small or even token facilities to compensate.

Imperial naval depots (Supp. 9, p. 7) exist one per sector, or at minimum one per 16 subsectors. As described, these must be enormously expensive.

Army Forces

Planetary Defense Forces

In accordance with "Troops of the Fifth Frontier War" (JTAS #10, pp. 24-25), the average Imperial world has a defensive troop strength of 1,800 battalions (900,000 troops); this drops to 1,730 (870,000 troops) if we ignore tech levels less than 5.

Colonial Army

Colonial army forces in FFW appear to be exactly those generated as mobile battalions per JTAS #10, pp. 25-26: 53 battalions (26,000 troops) per world on average; 49 battalions (25,000 troops) per world ignoring tech levels below 5.

Imperial Army

Imperial army forces in FFW (including mercenaries) initially number 10% (198 vs. 1968 battalions) of the colonial army strength, not including battalions less than tech level 5 (JTAS #10, p. 25). Assuming this is typical, the Imperial Army amounts to between 130 and 260 battalions per subsector; average 200 battalions. This accords well with the estimate of Imperial Navy assault squadrons, above (one per three subsectors, with a capacity of 600 battalions).


I will continue to use "a short description of incomes and expenses of planetary armies in Traveller" (Striker, Book 2, pp. 38-39) until a replacement is offered.

Gross National Product

Per Book 3, the average world in Traveller has a population of 340 million; population-weighted average tech level is 10.5. Average annual per capita GNP (including trade class factors) is 12,100 local credits, or 7,700 Imperial credits (exchange rate: 0.63). Average GNP per world is 4,200 billion local credits, or 2,600 billion Imperial credits.

Local Military Spending

Worlds spend between 1% and 15% of their GNP on the military, depending on the relative degree of international and interstellar tension and conflict; the average is 3%. Of this, 30% goes to the Imperium for the maintenance of the Imperial military (Striker, Book 2, p. 38). The remainder amounts to between 29 and 440 billion credits per world per year, with an average of 87 billion credits.

The total military expenditure per person ranges from Cr120 to Cr1,800, with the average Cr360.

Army Forces

The army portion of these expenditures is 40% on worlds with significant atmospheres (5/6 of the total), but only 6% where there is a vacuum or trace atmosphere (1/6; ibid.). This works out to an army budget of between 10 and 150 billion credits, averaging 3 billion credits, to pay for a planetary defense force (including the mobile forces forming the colonial army) of 1,800 battalions.

The yearly expenditure per soldier is therefore between Cr11,100 and Cr167,000, averaging Cr33,000. This amount is divided between equipment maintenance (at 10% of purchase price per year), and all other expenses (at Cr10,000-50,000 per soldier, depending on quality; ibid.).

Picked troops (SMC, pp. 39-41; JTAS #12, pp. 42-45) appear to spend roughly double their personnel costs on equipment maintenance. Applying this factor to other quality levels implies that the average world can afford to maintain their army forces at the highest possible readiness in wartime (with some left over for replacements), but only militia-level quality (Cr30,000 per year) in ordinary circumstances and not even that after extended periods of peace. In this last case, significant portions (~70%) of the planetary defense battalions may be placed in a reserve status, at an estimated cost only 1/10 that of their active counterparts; this is sufficient to maintain the active forces at militia standards.

Naval Forces

The remaining 60-94% of local military spending goes to support naval forces, both planetary navies and the squadrons that make up the colonial navy. This amounts to between 19.1 and 290 billion credits per world, averaging 57 billion credits. In the absense of any better estimate, I will use 10% of purchase price per year (Adv. 5, p. 35) to represent the operating costs for naval forces(2). Purchase price factors are estimated by class of vessel, and calculated per dton:

capital ship             Cr  600,000
tender+riders            Cr  600,000
escorts and auxiliaries  Cr  250,000
system defense boats     Cr2,000,000

Planetary Navy

An average of 42 SDBs (17,000 to 420,000 dtons; median 84,000 dtons) per world cost between 3.4 and 84 billion credits per year to maintain; the median value is 16.9 billion. The median value is supportable at all levels of naval spending, ranging from 88% to 6% of expenditures (average 30%).

Colonial Navy

The number of colonial navy squadrons in a subsector is directly correlated with the number of high population worlds. It is therefore reasonable to talk about the average expenditure per world within the subsector, even though only certain worlds are actually constructing and contributing squadrons.

An average subsector, with colonial squadrons ranging from 2.7 to 25 million dtons, total (median 7.4 million dtons), spends 85 to 1,220 billion (median 310 billion) credits to maintain its navy. Per world, this is an average annual expenditure of 2.2 to 31 billion (median 7.7 billion) credits. The median value ranges from 40% to 3% of naval expenditures (average 14%). Taken together with the cost of the planetary navy, this represents 43% of the average case, leaving a wide margin for maintaining local bases and other support functions. This spending level exceeds the available budget after long periods of peace (129%), implying that a portion (~30% by cost) of the available forces may be placed in ordinary (Adv. 5, p. 35) to reduce costs.

Imperial Military Spending

After applying exchange rates, the revenues available to support Imperial military spending range from 320 to 4,700 billion credits, averaging around 950 billion credits per subsector(3).

Imperial Army

The Imperial Army consists of between 130 and 260 (average 200) battalions of long service professional troops per subsector. Applying the same cost factors as before, these forces cost between 5.9 and 11.7 billion credits to maintain, with the average around 9 billion credits.

Imperial Navy

Squadron operations for 2.4 to 10.4 million dtons per subsector (median 4.6 million dtons) cost between 67 and 420 billion credits (median 158 billion credits) per year to maintain.

Together, visible Imperial military spending accounts for between 73 and 430 billion credits annually (median 167 billion credits): 8% to 45% of the average budget. There should be plenty of funds remaining for fleet headquarters, support functions, naval bases, contributions to the sector depot, and so on. Even if the actual stellar density across the Imperium is closer to that depicted in the canonical sectors than in the rules as written (1/3, rather than 1/2), visible spending remains within acceptable limits (11-68%).


To the extent that my assumptions are valid, I conclude that the military forces and spending levels depicted in classic Traveller are reasonable and internally consistent across a wide variety of references and citations -- rules, games, articles, JTAS news entries, etc.

I noted up front that incorporating population modifiers ex post facto would have a profound effect on the forces depicted here. In fact, it appears that this leads directly to the massive force levels mentioned for MegaTraveller (Rebellion Sourcebook, p. 27): two fleets of 50-100 capital ships each per subsector. Maintaining the original feel of the classic Traveller Imperium (c. 1981-1985) after correcting for population modifiers would require a corresponding reduction in available funds for military spending.


(1) The capabilities of the "system defense boats" in FFW and I:E are fairly well established and internally consistent. The number of SDB's defending Terra in I:E (1,700) matches the SDB figures from FFW (1,500-2,000, depending on TL). In FFW, 10x TL9-10 SDB's appear to be about equal in killing power to one starship attack factor. Against a comparable number of bombardment factors, they suffer 30-40% casualties per attack. A wing of 50 SDB's in I:E has on average combat power equal to the lightest Colonial Cruiser Squadron in the game, but less capable defenses (0-2-4, vs. 0-2-6). A squadron of cruisers could total as little as 40,000 dtons and won't top 1,000,000 dtons, including escorts. Non-jump warships are roughly as effective as twice the tonnage of jump-capable warships.

I infer, therefore, that the SDB's depicted in FFW/I:E can range from 400 dtons to a maximum of about 10,000 dtons. This also corresponds with the lower bound mentioned for battleriders (10,000 dtons, Book 5, p. 19). Since "... SDB's are loaded into 10,000-ton or 20,000-ton bulk carriers..." (Supp. 9, p. 25), the median is likely to be at the lower end -- e.g., 2,000 dtons (geometric mean).

(2) I infer this includes (Adv. 5, p. 8) personnel costs, ship operating expenses (including fuel, environment, overhaul, life support), ammunition (including reloads, expendable items, missiles, and spare parts), ship's locker, and battle damage field repairs (ibid., p. 34). All other expenses, including especially supporting facilities, are accounted separately.

(3) Taken literally, the rules (Striker, Book 2, pp. 38-39) imply that the level of Imperial funding depends on the aggregate spending habits of its member worlds. While this is possible, I suspect that each world's contribution is actually negotiated in advance and relatively stable.

Copyright (c) 2005 by Christopher B. Thrash

The Traveller game in all forms is owned by Far Future Enterprises. Copyright (c) 1977 - 2005 Far Future Enterprises. Traveller is a registered trademark of Far Future Enterprises.



This page hosted by PrismNet.