Traveller ATU: Re-Expansion

Imperial Reconquest

There are two types of re-expansion setting i could get into which I’ll call re-expansion and reconquest.


Imperial Re-expansion

One way to get the feel of the original Traveller novels – a collection of worlds that appear largely self-contained without a central authority – is an Imperial re-expansion.

In that kind of setting there has been an empire in the past and that empire settled numerous colonies but then some kind of collapse occurred before the individual colonies had developed to the level of star travel. In the collapse the colonies that survived reverted somewhat in technology and then either stayed there or clawed their way back.

The imperial world recovers and starts to re-expand and the players start on the far edge of that expansion – conquest and naval battles and invasions are happening but it’s happening a couple of sub-sectors away. So it’s a mixture of a frontier type setting and a Star Trek “boldly go, find new worlds” type setting.

The key point with this back story is to create a specific backdrop where most of the planets were settled by humans from the same culture but who developed in many different directions during the Dark Age allowing plenty of room for the imagination.


Imperial Reconquest

Another option is during the Dark Age many of the original colonies developed all the way up back up to jump travel and created their own pocket empires with their own fleets and the new Imperium are conquering them one by one Rome style with the players right at the cutting edge of the war zone.

This kind of setting wouldn’t inspire me much except as the background for a war game or if the players were into being Imperial agents involved in diplomacy, spying, sabotage etc – so basically they’d be given missions rather than random travelling. I’m not likely to ever do it as a i like frontier settings better however I was thinking about the possible backdrop to a setting like this so these are some notes for future reference maybe.



I haven’t looked at the 3rd Imperium timeline yet but I’d use the OTU as the basis for this. It doesn’t have to be 100% consistent with the canon data as this setting will be some time in the past.


Starting Assumptions


Treat “fleet” in an abstract way meaning one unit of military force


Alpha worlds – those with high pop and tech level – are the only ones that matter militarily as they are the only systems that can produce fleets


Exception – the systems needed as refueling stops in between the Alpha worlds


On average there is one Alpha world per sub-sector and they expanded out into their sub-sector claiming worlds in their hinterland for their mini empire


The 3I expanded out in all directions from Capital into Core sector and then beyond


At start the 3I roughly has the eight sectors around Core and a finger has expanded through Corridor into Deneb as well

so say the 3I has c. 120 sub-sectors or 120 fleets – with another 8 in a finger through Corridor and Deneb (which is still in the throes of being pacified) and c. 40 border sub-sectors with a home fleet each leaves around 80 fleets and around ten sector fronts – so say 8 to each front on average.


The Deneb command has 8 fleets available but they are actively engaged most of the time with unconquered systems, Vargr and rebellions. At any one time any number from 0 to 8 might be available but the larger the number the shorter the time available – plus they could be called away any time to deal with an emergency elsewhere. (If it was a board game the player might get 0-4 imperial fleets each year or something).


The Zhodani haven’t fully expanded into their sub-sectors yet – they have trade agreements and alliances etc but not fully integrated systems so those sub-sectors are mostly neutral at the beginning and the Zhodani aren’t very involved – at least at the beginning.


Trin (and its pocket empire) has signed an alliance with the Imperium and Trin is the center of 3I activity in the Spinward Marches. Trin’s fleet and one imperial fleet are on guard.


The pocket empires facing the 3I are listed below – subject to change if it doesn’t fit with timeline or other OTU stuff. The list doesn’t have to be entirely consistent with the canon data as I’m assuming a lot of these worlds will be severely damaged in the conquest era so their pop and TL stats could have been higher.

  • Jewell
  • Efate
  • Ruie (damaged)(subjugates Regina at start)
  • Algine (damaged)
  • Aramanx (damaged)
  • Vilis
  • Heroni / Natoko (damaged) (confederation)
  • Porozlo (subjugates Rhylanor at start)
  • Mora / Fornice (atmos damaged?)
  • Palique (atmos damaged?)
  • Lunion / Strouden
  • Gram / Sacnoth (sword worlds)
  • Mire (Darrian) (higher tech)
  • Iderati (five sisters)
  • Collace (District 268)
  • Glisten / Tirem
  • Robin? (damaged)(refugees to Dodds?)

so c. 20 fleets in all divided up into multiple small alliances


Caesar’s Conquest of Gaul

The idea here is to treat the setting a bit like Caesar’s Gallic Wars with the pocket empires as similar to the Gallic tribes, disunited and split  into various alliances who are hostile to each other or at least distrusting and competitive.

The 3I’s strategy is to insert itself into local politics, taking sides in disputes and using a combination of diplomacy, bribes, assassination, sabotage and occasionally outright war to take advantage of any opportunities that arise to add new Alpha systems and their retainer systems to the empire.


In the Traveller setting there was an earlier human Empire which collapsed. The current Imperium was rebuilt over the top of the previous from the same core. So imagining the situation 200 years after the collapse what kind of planetary options would there be?

1. Core worlds – as before

2. Colonized worlds where the colonists die out during the collapse – hostile mining worlds, planetoids etc – so lots of ruins.

3. Colonized worlds with a native prestellar species where the colonists might have died out or been killed by the natives or become like the natives or enslaved by the natives.

4. Colonized worlds where the colonists reverted in technology.

5. Colonized worlds with a prestellar native species where the colonists reverted in technology – maybe to the same level as the native species or still above (see Jorune or Tekumel).

6. Non-colonized worlds – maybe with a science base or two – with a prestellar species.

7. Other non-colonized worlds.

This setting could take one of the existing Imperium sub-sectors near the core with their exisitng planetary profiles, ignore the government, tech level, starport stuff and just keep the physical characteristics: size, atmosphere etc with the players operating at the edge of the expanding Imperial frontier whether for some official part of the Imperium , a commercial org or as freelance antique hunters looking for Vilani artifacts.


Dividing the planets into three categories: habitable, habitable impaired, uninhabitable and assuming the original subsector capital was the best planet some random tables might be:

sentient alien species: habitable 8+, habitable impaired 10+ uninhabitable 12+ (these last would generally be very weird e.g. lava creatures.

previous colony: habitable 8+, habitable impaired 10+ uninhabitable 12+.

If previous colony and no sentient species, colony survived: habitable 8+, habitable impaired 10+, uninhabitable 12+ (a surviving colony on an uninhabitable planet may have survived in a strange form e.g. tunnel dwelling cannibals)

If previous colony and a sentient species: hostile relationship 2-5 neutral relationship 6-8, friendly relationship 9+

colony survival?

hostile relationship: habitable survived 10+, habitable impaired 11+, uninhabitable 12 (maybe in some strange brain in a jar type form)