Freelance Traveller

Sizing Your Campaign: Thoughts on Campaign and Ship Sizes

by Ken Pick

This article appeared in the July/August 2025 issue.

I do. 

I have been an Old Traveller Hand since my then-regular DM (Dungeonmaster, not Dice Modifier) Wayne Shaw introduced me to a box of three little black books in the fall of 1977; my entire hands-on experience has been Old School, Classic Traveller (“Traveller Mk.I”), MegaTraveller (“Traveller Mk.II”), and a homebrew hybrid (“TravQuest”) in the 1980s using Chaosium’s Runequest/BRP/ARP percentile system.

None of this was in any official Traveller universe (a.k.a. the Third Imperium), only that Burgess Shale wild variety of original homespun settings. And these are my observations over my now-12 Terms as a Traveller:

In retrospect, Traveller Mk.I (1977) seemed designed around small-area, small-ship campaigns with “moderate” Tech Levels. Not that much high-tech, a lot like Firefly or The Expanse with Jump Drives.

Aside: Firefly (a.k.a. “The Outlaw Josey Wales in Space”) has many of the same tropes as Traveller Mk.I - Free Traders like the Beowulf or Boxcars or Serenity misbehaving out on the Rim, small campaign area (Firefly’s “Verse” of 35 Ophiuchi would Travellerize as a small isolated Jump-1 star cluster), fairly-low future tech similar to H Beam Piper (primarily fusion power, antigravity, and Maneuver and Jump Drives) and no actual aliens. However the connection is probably the other way around, and not just meta-chronologically. My writing partner/spy at TravCon 2022 heard Joss Whedon played what had to have been Traveller in his college days. (His first impression of Firefly was “This is Joss Whedon’s Traveller campaign!” and it seems he was right.)

But Traveller first appeared in 1977, only months after the premiere of Star Wars, with its Galaxy-sized Empire and multi-klick-long starships. The only other widespread universe paradigm was Star Trek, another big-ship universe with ultra-high “Trek Tech” (estimated Tech Level 18). Both of these paradigms – at the time, the only ones in town – emphasized big ships, maxed-out technology, and a wide-ranging campaign area.

Accordingly, early Traveller campaigns in my experience tried to push the limit, attempting large ships (up to tens of kilotons), a ruling Tech Level of 13-15, and campaign maps of several subsectors. Experience showed most of the in-game action (player-character/lone Free Trader level) would often fit within a single subsector.

And GDW responded with “Hold my beer and watch this”, i.e.  High Guard and the offical Traveller campaign background of the Third Imperium around 1979-1980 – big ships (up to one megaton) in a big (2000-subsector) campaign map. I can understand the meta-reason for the Imperium – a large diffuse interstellar empire gives a common background and standards yet allows GMs to set up their own stuff far away from anyone else (including the official campaigns like the Spinward Marches) on the Rim where the action is. But it still doesn’t make much sense from a worldbuilding and/or player perspective – the scale is so great that any small group of characters puttering around in a Free Trader is going to shrink to insignificance.

Campaign Size Categories

These are my Campaign Size classifications for Traveller campaign universes.

• Small-area: Within one Traveller subsector (80 hexes, 25-40 systems); example Firefly.
• Medium-area: Within one Traveller sector (16 subsectors, 1280 hexes, 430-640 systems); examples Shavian Empire (9 subsectors), Foible Federation (8-10 subsectors), Spinward Marches (full sector).
• Large-area: More than one Traveller sector; examples Star Trek, Palpatine Empire (Star Wars), Third Imperium (23 sectors/350+ subsectors/100k-150k systems within its borders, 120 sectors/1900+ subsectors/500k-750k systems in full map including surrounding areas).

Ship Size Categories

And for ship sizes within those campaign universes:

Small-ship Campaign: Book II designs with a maximum size 5-6000 dtons (12000 dtons with “Beyond Book II” High Guard retrofits).

A small-ship campaign’s warships (with the 12000-dton ship size limit from “Beyond Book II”) would break down into 3-4 size classifications:

• Corvettes of under 1000 dtons and measured in hundreds of dtons.
• Destroyers of  1000-5000 dtons (the lower half of the kiloton range) The smallest of these (1000-dton range) would be called Destroyer Escorts (TL6-7 US Navy definition, equivalent of TL8-9 NATO-terminology “Frigates”).
• Cruisers would be the upper half of the kiloton range, from 6000-12000 dtons.
• With an optional classification of Frigate (TL7 US Navy definition, either a very big Destroyer or very small Cruiser) at the 6000 dton border between the two.

Medium-ship Campaign: High Guard designs or hybrids of “Beyond Book II” and High Guard with a maximum size in tens of thousands of dtons, usually based on WW2-era ship tonnages; examples Shavian Empire and Foible Federation.

A medium-ship campaign adds larger battleships to the high end of the small-ship campaign; the Shavian Empire’s Navy is typical:

• Corvettes remain under 1000 dtons, just as in a small-ship campaign.
• Destroyers of 1000 but under 10000 dtons, measured in kilotons. As with the small-ship campaign, the smallest of these are called Destroyer Escorts and the largest might or might not be called Frigates.
• Cruisers are divided into Light Cruisers of around 10000 dtons (without spinal mounts) and Heavy Cruisers of around 20000 dtons (with minimum-sized spinal mounts of 1000 dtons),
• Battlecruisers are in the 30000-dton range, Battleships around 40000, and Capital Ships around 50-60000; all of these pack spinal mounts, usually of medium size (2-5000 dtons).

Large-ship Campaign: Full-honk High Guard designs, up to the High Guard maximum of one million dtons; examples Star Trek, Palpatine Empire (Star Wars), Third Imperium/Supplement 9: Fighting Ships.

A large-ship campaign breaks down into four generic warship sizes:

• Corvettes are the same as the small- and medium-ship campaigns.
• Destroyers of at least 1kt but under 10kt, measured in kilotons. Other than that, same as the medium-ship campaign though without the subtype of Frigate.,
• Cruisers of at least 10kt but under 100kt, measured in tens of kilotons, Divided into Light Cruisers without spinal mounts and Heavy Cruisers and Armored Cruisers with low-end (t-2kt) spinal mounts. The difference between Heavy and Armored cruisers is the former emphasize maxed-out Maneuver Drives at the expense of protection (armor and screens) and the latter emphasize maximum protection at the cost of M-Drive performance.
• Battleships of 100kt and up, measured in hundreds of kilotons and packing large (5-8kt) spinal mounts. The Third Imperium fields “Dreadnaughts” of 200+kt with M6J4 prerformance; as in HMS Hood and her planned follow-ons at TL5, the only way to build a true fast battleship is to make the ship bigger. Which leads to “Death Star Syndrome” as bigger ships are more expensive (maybe too expensive to risk), fewer can be built and commissioned, and they can't be everywhere at once.

To maximize the number of ships with large spinals in the sky, a tonnage of 100kt (such as the Third Imperium's M4J4 Inkaallur in FASA’s Far Traveller #2, 1983) would be more likely, but at a cost in performance, protection, or both. Like TL5 wet navies, this results in a split into Battlecruisers (maximized performance at the cost of protection) and Battleships (maximized protection at the cost of performance) just like the split between Heavy Cruisers and Armored Cruisers.

Tech Level Classifications

Tech levels are a bit more abstract; the minimum for Jump Drive is TL9, the scale tops out at TL15 with the possibility of super-high TL16+ (i.e. Star Trek, the Ancients, the unnamed Forerunners in The Expanse, or Clarke’s Third Law). This breaks down into five Tech Level ranges separated by “Tech Level Plateaus” where technological advances can stall with no actual advance.until a paradigm-shifting breakthrough:

• Tech Level 0 (Pre-Agricultural, Pre-Civilization):  Stone Age hunter/gatherer tribes, too busy surviving to do anything else; the TL0 Plateau is a Fermi Great Filter3, stalled until they can develop Agriculture and group into large enough settlements to organize above the Gov 0 family/tribal level.
• Tech Levels 1-3 (Pre-Industrial):  Bronze/Iron Age nation-states and empires (Rome, China, Spanish, early British, etc); the TL3 Plateau is another Fermi Great Filter, limited by power sources (muscle, animal, wind, water), waiting on an Industrial Revolution’s power sources (steam and later electricity) allowing mechanization and large-scale production. Most civilizations stall at this plateau and advance no further.
• Tech Levels 4-7 (Industrial Age):  Steam and fossil fuel power (and eventually nuclear fission) allows industrial economy and related tech advances including electricity and primitive electronics; the TL7 Plateau is the lack of solid-state electronics severely limiting compute power, automation, and networking same through complex electronic communications. Though time spent at this Tech Level allows the civilization to refine and adapt before the disruption of TL8’s solid-state electronics bringing about the Information Age relatively overnight. Generally the longer a world spends at the TL7 Plateau, the more likely it is to survive the TL11 Plateau. Note that Earth developed solid-state electronics early and breezed through the TL7 Plateau like it wasn’t there.
• Tech Levels 8-11 (Information Age): Compact powerful computers, networking, early Artificial Intelligence, and electronic/cyber everything leads to global communication/networking for good, bad, and ugly; the TL11 Plateau is the civilization turning their back on anything other than themselves and concentrating entirely on internal matters, stalling on-planet without much spacefaring, much technological thrashing without any net advance, and general narcissism/hedonism/brain rot often manifesting as “Cyberpunk Syndrome” techno-dystopia with Gov 3s dominating. Limited in thinking to “their planet and some lights in the sky” and “who has the most toys” and lubricated by the Zero-Sum Game: “Since there’s only so many resources to go around on our One Little Planet, the only way to get more for Me is to take it away from You.”
• Tech Levels 12-15 (Interstellar Age):  Paradigm shifts to space-centered, “going down to planet surface” instead of “going up into space”, liberating a civilization from the TL11 Plateau’s Limits to Growth; the TL15 Plateau is the “firehose into the teacup limit” of information overload a human brain can handle, even with cyberassistance.

This translates into Traveller campaigns as follows; Maneuver Drives, Powerplants, and Jump Drives (the Traveller Triad allowing affordable space/interstellar travel) come into play around TL9, “field-effect drives”/antigravity (improving space travel capability) around the same time, and everything tops out at TL15 with the possibility of super-high TL16+ (i.e. Star Trek, the Ancients, the unnamed Forerunners in The Expanse, or Clarke’s Third Law). This tends to break into three general campaign Tech Levels:

• Low-tech Traveller: TL9 or 10 maximum; not that much advanced from today’s TL9 with the addition of Jump-1 Drive. May or may not have Acceleration Field-effect (Grav) sublight drives.
• Lack of Acceleration-field technology results in something like The Expanse with Jump-1; no Grav vehicles, artificial gravity only by spin or acceleration, high-efficiency fusion-torch  Maneuver Drives similar to The Expanse’s Epstein Drive, with all the limitations of same.
• Medium-tech Traveller: TL12 maximum (allows for Jump-3); internally considered the threshold of interstellar community.
• High-tech Traveller: TL15 maximum.

These are maximum Tech Levels for the highest-tech worlds, representing “gee-whiz” technology compared to the "ruling" widespread TLs of the campaign, one or two  levels below the maximum.

Aside: “We're at Tech Level 9 IRL; where the hell is my flying Grav car?” Answerable as “We didn't discover Grav technology IRL until TL14, but when we did we realized we could have had it at TL9 If We Only Knew...”

Gedankenexperiment: “Low-Tech Traveller”

Some time in the 1990s, I tried a thought-experiment: What would a smaller milieu, a small-ship, small-area, lower-tech campaign be like? Depending on whether you have acceleration-field technology (gravs and reactionless field-effect drives) or not, you get something like Aliens, Firefly/Serenity or The Expanse with Jump Drives.

• Small Area: One subsector (two max), with a ruling interstellar Tech Level of 11, with some “gee-whiz” cutting-edge TL12 here and there and the possibility of higher-tech from “rooning” (rare) Forerunner artifacts. No big interstellar overgovernment, maybe some “pocket empires” of dominant systems and their secondary colonies.
• Small Ships to match the small area but still retaining some High Guard-era stuff.
• Medium Tech, with a de facto cap around TL12. (No powered armor or high-energy hand weapons...)

This was the origin of “Beyond Book II” and most of my world writeups in Jump Destinations, a fairly-generic overview of small-ships in a relatively-small area of loosely-aligned worlds and pocket empires (the largest smaller than a subsector), recovering and re-civilizing after a Long Night. Not as settled and “too old to die” like a Third Imperium, but underpopulated with a semi-frontier atmopshere. Small navies of smaller (12kt or less) ships and the possibility of deep exploration into the Unknown outside the one- or two-subsector civilized area.

Setting the ruling Tech Level at 11 with a max of 12 not only gave an atmosphere like Aliens but also had an effect on Jump Drives. TL12 max gives us Jump-3 max, with Jump-1 and Jump-2 the norm. Which tends to select for a small-to-medium area; a “good long trip” would mean maybe into the next subsector, and the time in Jump breaks down very clean if you go from “Moves you X hexes in one week-long strategic turn” to an actual FTL speed paradigm:

• Jump-1 moves you one hex in 6 days (instead of 7 - Jumpspace observes Shabbot?).
• Jump-2 one hex every 3 days (twice as fast as Jump-1).
• Jump-3 one hex every 2 days (3x as fact as Jump-1).

Miscellaneous Rules of Thumb I’ve Been Assuming:

No more than one alien race per subsector (exceptions for those races endemic from the prior civilization cycle like Humaniti and Vargr). This later expanded into two “Fermi Paradox Great Filter” assumptions:

• A limited “Rare Earth Hypothesis” assuming only one life-bearing world in ten ever gets beyond bacteria. If the world’s microbes get through an Oxygenation Event, there could be worlds with a somewhat-breathable atmosphere ready for terraforming. (This was the rationale behind my Jump Destinations of the Dole Moving Group.)
• A further Fermi Great Filter for actual alien races assuming only one in ten ever advance beyond the TL3 Plateau (one in a hundred if you add a TL0 Plateau where they never get beyond stone-age hunter/gatherer tribes; Mesoamerican civilizations were right on the boundary between TLs 0 and 1).

Peacetime Naval sizes of 100kt of each major combatant type per subsector, pro-rated by the navy’s sphere of influence. Major combatants are limited, and must be used wisely – no sky filling-fleets from small successor states, no matter what Star Wars: The Force Awakens says or does. (The 100kt/subsector limit is not a hard-and-fast law but more a general rule-of-thumb; wartime mobilization may allow a wartime fleet 2-3× larger.)

Here are a few examples (interstellar capability only, not counting insystem defense assets) at the 100kt/subsector limit:

Telerine, Paryan System – Small-area, small-ship, medium-tech. TL11 (Jump-2 max), three-system Jump-1 pocket empire (Paryan, Virtchok, and Hamilton’s Star).

Three  major combatants: one 12000-dton Cruiser and two 4-5000-dton general-purpose Frigates; remainder are light escorts & corvettes.

Grenna, Boreas System – Small-area, small-ship, low-tech. TL 9bis (Jump-1 max, imports J-2 drives), Telerine’s rival in the Dole Moving Group, two-system Jump-1 pocket empire (Boreas and Pojhola, a red dwarf Wayport connecting to the interstellar mains).

Major combatants are two 8000-dton Cruisers (both license-built abroad), the remainder being smaller Destroyers/Escorts and Corvettes augmented by contracted privateers.

Thermidor, Zrath System – Small-area, small-ship, medium-tech. TL12 (Jump-3 max), Thermie Navy can Power Project up to three hexes range. TL12bis is the dividing line between a (TL12-) fighter carrier and missile navy and a (TL13+) spinal-mount battleship navy.

Five major combatants: two 12000-dton Carriers (120 fighters each), three 8000-dton Cruisers (40 fighters each); four 4kt Escort Destroyers to screen and defend the Carriers; remainder are Destroyer Escorts and Corvettes. (Including the Torpilleur-classhttps://www.freelancetraveller.com/features/shipyard/classic/ken-pick/torpilleur.html and https://www.freelancetraveller.com/features/shipyard/classic/ken-pick/grantorp.html missile corvettes and SDBs, a Thermidorian design with the highest firepower-to-size ratio of any ship in the sky.)

Unirion/Bios/Triott/Quantol/Pentothon, Pentathos System – From “The Scattered Worlds”, Wayne Shaw’s high-school attempts at space opera. On the boundary between small- and medium-size, medium-ship, high-tech. TL14 (theoretical max Jump-5, practical max Jump-3), dominant system over half a subsector. On the battleship navy side of the TL12bis dividing line, where fighters and missiles yield to spinal Meson Guns as the primary anti-ship weapon. Patterned after a Shavian Empire subsector fleet, as both had the same meta-origin.

About Eighteen major combatants:

• Five capital ships: two 36000-dton Battleships with 4000-dton spinal-mount meson guns, three 24kt Pocket Battleships with 2kt spinal mounts. Built mostly under High Guard with  “Beyond Book II” laser bays and engine clusters. Each ship carries 40 fighters.
• Six to eight Cruisers of 8-12000 dtons. Built mostly under “Beyond Book II” with High Guard meson screens and meson gun bays on one or two cruisers. Each cruiser carries 40 fighters.
• Six 6000-dton Frigates (often detached to their Scout Service for deep-exploration missions like the original Starship Enterprise),

Remainder are smaller Destroyers, Escorts,  and Corvettes; Battleship and Cruiser strength matches that of the TL6 German Navy of 1939-40.

Compared to Shavian Empire warships, Pentie Battleships are intermediate between Shavian Battlecruisers and Battleships, Pocket Battleships intermediate between Heavy Cruisers and Battlecruisers, and both Battleships and Pockets are M5J3 performance standards instead of the Shavian Empire’s M3J3.

 

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