#Wargame Wednesday – Searching for My Strategic #TravellerRPG Wargame

In a recent post I discussed my search for a #TravellerRPG wargame for use in ground combat. In the course of that posting, I talked about several different wargames and what I liked, or didn’t like, about them. Since I started down that rabbit hole, I decided to dig a bit further by taking a deeper look back at the original combat systems from the Classic Traveller-era (1977-1981).

The Traveller Combat System

Along this voyage of (re)discovery I came to the realization that there is no one single “Traveller Combat System.” Between 1977 and 1981 Game Designers’ Workshop (GDW) gave us EIGHT (8) different ground combat systems “For Use with TRAVELLER.” Broadly speaking, I see the eight systems divided into two broad categories; Strategic and Personal/Tactical. The eight systems, many found within their own games, are:

  • Imperium, Classic Traveller Game 0, 1977 (Strategic)
  • Traveller Combat System, found in Classic Traveller Book 1: Characters and Combat, 1977 (Personal)
  • Mercenary, found in Classic Traveller Book 4: Mercenary, 1978 (Tactical?)
  • Snapshot, Classic Traveller Game 2, 1979 (Personal)
  • Azhanti High Lightning, Classic Traveller Game 3, 1980 (Personal)
  • Fifth Frontier War, Classic Traveller Game 4, 1981 (Strategic)
  • Invasion Earth, Classic Traveller Game 6, 1981 (Strategic)
  • Striker, Classic Traveller Game 7, 1981 (Tactical)

[Of note, Dark Nebula, Classic Traveller Game 5 (1980) is basically a reskinned Imperium and I don’t treat it as a separate game system.]

In this post I’m going to look at the Strategic combat systems for the Traveller roleplaying game. Let us begin by going back to the beginnings of the RPG hobby in the mid-1970’s and a little corner of Indiana with a group calling themselves Game Designers’ Workshop (and pay attention to where the apostrophe is placed).

Strategic Traveller Wargames

Imperium – Empires in Conflict: Worlds in Balance (1977)

Imperium (GDW 1990 Edition)

Imperium is known as Classic Traveller Game 0. The number reflects the fact the design predates release of the Traveller RPG system. As author Shannon Applecline tells us in Designers and Dragons: The ’70s

Meanwhile, GDW was still playing with science-fiction designs. In 1975 and 1976 they worked on the prototype of a wargame called Imperium (1977). They finally published it in 1977 in a very different form, but in its original incarnation Imperium imagined a war between humans and many alien races, among them the lion-like Aslan, the bee-like Hivers, the dog-like Vargr and the mercenary Dorsai. Imperium also provided rules for individual characters — the sons of the leaders of the war — who progressed through individual careers and provided bonuses to armies based on the careers selected.

Both the alien races and the careers would be incorporated into GDW’s second and most notable RPG: Traveller.

Shannon Applecline, Designers and Dragons: The 70’s, Evil Hat Productions, 2014, p. 158

Here is how Imperium introduces itself:

lmperium is a science-fiction game about interstellar war. Several hundred years from now, Terra reaches the stars, only to find that they are already owned by a vast, sprawling interstellar empire: the Ziru Sirka (the Grand Empire of Stars or Imperium). The heavy hand of the lmperium and the expansionism of Earth lead naturally and inexorably to interstellar war. lmperium is a boardgame of that conflict.

Imperium Rule Book, p. 2

Imperium is what I term a grand strategic wargame. The scale of the game is six-month turns and 1/2 parsec (1.67 light years) per hex. If you are a Traveller RPG aficionado, you probably recognize the map scale is different and not the usual 1-parsec per hex. In keeping with the grand strategy design, Imperium includes rules for economics and both space and planetary warfare. The game actually has three distinct combat subsystems; “Space Combat,” “Planetary Surface/Space Interactions,” and “Surface Combat.” In this post I am focusing on the ground warfare aspects of the design found in the rules for “Surface Combat” in the core Rule Book starting on page 8.

If one makes it past the Space Combat and Planetary Surface/Space Interactions phases of an Imperium game turn (representing the deep and close-space battles) then a Surface Combat action may be fought. The combat mechanic here is the very traditional “battleline” where opponents are paired up. There is a very Avalon Hill War at Sea-like vibe to this combat mechanic and given WaS was published in 1975 is it possible the GDW designers took some inspiration?

In Imperium, Surface Combat begins with both players taking their forces and “pairing them off” against each other. If the attacker is unable to pair-off against all the defenders, no planetary assault is possible. If all combatants have been paired, any excess combatants can be doubled or even tripled up against. Optionally, forces not engaged can be “screened” and will not participate in the battle.

[As I reread the Surface Combat rules closely, I realized I had missed an important element over the many years played. I always assumed that only Troops, Planetary Defense Markers, and Outposts participated in Surface Combat. However, ships also participate!]

Paired off Imperium combatants now fight a round of combat by first determining their combat differential and then rolling on the appropriate column of the Surface Combat Results table. Regular troops attacking jump troops are given a round of defensive fire before the jump troops fire back to simulate the lack of heavy firepower jump troops possess (i.e. jump troops are great on offense but poor on defense). Possible combat results are either “No Effect” or “Destroyed/Neutralized.” Surface combat continues in rounds until all committed troops of one side are eliminated.

Surface Combat in Imperium, indeed any combat in Imperium, does not factor in a tech level difference. In the history of the game, the combatants were actually balanced technologically (although they designed ships using different doctrines) until the advent of the Terran battleship which appears in an Optional Rule.

Fifth Frontier War: Battles for the Spinward Marches (1981)

Fifth Frontier War (GDW, 1981) Rule Book

The cover of the rule book for Fifth Frontier War (FFW) carries the tagline “For Use With TRAVELLER” above the title. Here is how the game introduces itself:

Poised just beyond the frontier of the Imperium stand the war fleets of the Zhodani Consulate. Four times in the past five hundred years, they have attacked in campaigns to wrest control of the vital resources and rich worlds of the Spinward Marches from the Third Imperium. Now they strike again, and the Fifth Frontier War begins in earnest.

Fifth Frontier War is a Traveller campaign game portraying the progress of a far-reaching interstellar war and its effects on the many worlds that are its battlefield. The game is playable independently as a tense, fast-moving simulation of interstellar war. Rules cover starship squadrons and space battles, troop units and worlds at war, and the details of long-range interstellar planning. Special rules cover the operation of ship fleets, the use of naval bases, troop carriers, and advanced technological levels. Special charts cover every aspect of combat during the game.

Fifth Frontier War includes a large, four-color map of part of the Spinward Marches, complete with planetary surface boxes detailing the many planets within the area. Three sheets totaling 720 die-cut counters provide starship squadrons, troop units, fleet markers, admirals, and other details essential to the game. The rules booklet details how to play the game, while charts provide reference information. Two dice are included to help generate random numbers for combat.

Fifth Frontier War is playable by itself, but familiarity with the Traveller science-fiction role-playing system will aid in understanding the background history. The game may be played in 4 to 6 hours, and can usually be finished in an evening of play. It is designed for two players, but up to four may be involved if desired.

Fifth Frontier War, Rule Book, p. 2

The line, “…familiarity with the Traveller science-fiction role-playing system will aid in understanding the background history” is very insightful. FFW is set in the Traveller universe, but it is not an essential part of the roleplaying game. Like Imperium before it, FFW is another grand strategic wargame. This time, however, the setting is more closely tied to the Traveller material.

Leveraging the closer ties to Traveller, the scale in FFW uses several for the roleplaying game’s conventions. Each turn in one week, the same as the time spent in jump space, and each hex is one parsec.

FFW, like Imperium before it, uses several different combat subsystems in play. “Surface Combat” comes after “Space Combat” and “Interface Combat” in the Combat Phase of each turn. “Surface Combat” specifically deals with troops present on a world engaging in combat.

Resolution of surface combat in FFW is again very simple. The combat factor of a unit can be split to attack multiple defenders or they may combine with other units. The total of attacking combat factors is compared to defending combat factors to derive attack odds. Using the Troop Combat Results Table both the attacker rolls 2d6 and cross-references the results. Combat results are applied after all battles are complete. The combat result is expressed as the percentage of the force destroyed with the results applied at the end of the phase.

Technology makes a difference in surface combat in FFW. The combat factor of armored units is doubled in surface combat. Elite units also have their combat factor doubled. (Mercenary units have their strength halved if currently at 50% or more casualties; their heart isn’t in it anymore.) Most importantly, after the combat odds are determined, but before any dice are rolled, the relative tech levels of the force are considered. The difference in tech level becomes a column shift on the Troop Combat Results Table. Of note, the atmosphere of the planet is also a consideration, but appears in the form of a die roll modifier, not a column shift like technology. Just as importantly, the tech level of the force is determined by the lowest tech level unit participating in the combat.

Let’s see how surface combat plays out using the example in the rule book from FFW. It’s a bit long and the numbers may look big but in reality it goes quick once you try it. Pay close attention to how dramatic the column shifts can be from different tech levels fighting each other:

The Zhodani player has landed two tech level 14, full strength 20-factor troop units on a tech level 10 Imperial world having a tech level 15, full strength 5-factor troop unit and a 150-factor defense unit at 20% losses (thus having a current strength of 120). The Zhodani player attacks the Imperial troop unit using 15 factors; the combat odds are 3:1 (15:5) and are shifted one column to the left (to 2:1 ) due to tech level difference (14 -15 = -1 ). The dice roll is 5 and is not modified, as the atmosphere of the world is normal. Thus, 40% losses are inflicted on the Imperial troop unit. The Zhodani player attacks the defense unit using his remaining 25 factors. The combat odds are 1:5 (25:120) and are shifted four columns to the right (to 1.5:1) due to tech level difference (14 – 10 = 4). A 6 is rolled, and the unit takes 20% losses, increasing its total losses to 40%. Losses to the Imperial units are not implemented until the end of the combat. The Imperial player attacks one of the Zhodani units with all 5 of his tech level 15 factors. The combat odds are 1:5 (5:20). He could have used some of the factors from the defense unit to raise the odds, but this would have meant an unfavorable tech level difference due to the defense unit’s lower tech level. The tech level difference is (15 -14 =) 1, which means the attack is resolved on the 1:3 column. The dice roll is 9, and thus the attack has no effect. The Imperial player attacks the other Zhodani unit with the 120 factors of the defense unit. The odds are 5:1 (120:20) and are shifted four columns to the left (to 1:1) due to tech level difference (10 -14 = -4). The dice roll is 7, resulting in 10% losses to the Zhodani unit. Surface combat resolution is now finished for this world, and the combat results are implemented: a 10 casualty marker is stacked under one of the Zhodani units, a 40 casualty marker is stacked under the Imperial troop unit, and the 20 casualty marker for the defense battalions is exchanged for a 40 casualty marker.

Fifth Frontier War, Rule Book, p. 15

Near the end of the rules for FFW the designers give some hints for using this wargame in a Traveller RPG campaign:


Role-playing appears to Traveller players to be a simple series of adventures in which situations are presented, dealt with by the players, and resolved. The Traveller referee knows that there is a lot more to running a consistent, interesting Traveller campaign; preparation for each situation is required, contingencies must be foreseen, and background laid out. Fifth Frontier War is intended as a partial solution to the problems of presenting situations to Traveller players.


Fifth Frontier War is a detailed adventure game of the progress of the current war between the Imperium and the Zhodani in the Spinward Marches. It progresses on weekly turns with forces representing squadrons of military starships and battalions or more of fighting troops. The game is intended to be played for enjoyment of and by itself. Indeed, in situations where no referee is available, or where only two Traveller players can get together, Fifth Frontier War allows them to play a form of Traveller without a referee.

Ultimately, the Traveller referee will have enough experience with the game and its rules to be able to use it in a Traveller campaign. At that point, Fifth Frontier War can be used to indicate the greater conditions that are happening in the Spinward Marches, often just beyond the knowledge of Traveller adventurers. Players can be idly exploring a world in the Spinward Marches and be suddenly confronted with a major space battle in the skies above them, or encounter major friendly or enemy troop units establishing bases. The point is that they cannot know ahead of time exactly what activity is taking place even one system away, and that activity could be deadly to them.

Fifth Frontier War, Rule Book, p. 19

Invasion: Earth – The Final Battle of the Solomani Rim War (1981)

Invasion: Earth (GDW, 1981)

Invasion: Earth (IE) was released in the same year as FFW but does not carry the “For Use With TRAVELLER” tag across the cover. Maybe this is because Invasion: Earth is a historical game in the Traveller setting, taking place some five years before the default start of the Traveller setting from the Little Black Books.

Once again, I’m going to let the introduction of Invasion: Earth explain itself:


Invasion: Earth is a two-player game of the assault on Terra by the forces of the Imperium; this battle was the last major campaign of the Solomani Rim War. (A section at the end of the rules gives a brief outline of this war.) One player represents the commander of the lmperial invasion force and controls all lmperial regular, colonial, and mercenary units in the game. The other player represents the commander of the Solomani forces assigned to the defense of Terra and controls all Solomani units in the game.


Invasion: Earth is a complete game, playable in itself. It may also be used in several ways to supplement or to provide a background for Traveller campaigns and adventures, as indicated in a section following the rules on the play of the game.

Invasion: Earth, Rule Book, p. 3

Invasion: Earth is a game that shows the strategic-level of warfare, but at a much smaller scale than either Imperium or FFW. One game of Invasion: Earth is a single planetary invasion; one complete round of surface combat at one planet in Imperium or Fifth Frontier War. Each turn in Invasion: Earth is two weeks. Here is how the rules describe surface units:

Troop units are the field formations which, through the use of manpower and firepower, are the ultimate defenders or attackers of a piece of terrain. Due to the high technological levels of the opposing forces, the basic transport vehicle is the anti-gravity vehicle; hence troop units are quite mobile. PD [Planetary Defense] units are collections of energy weapons and missiles capable of engaging naval units bombarding the surface of a world. Each has an intrinsic garrison assigned to it; hence, a PD unit is rated and treated similarly as a troop unit. Most PD units are large, static installations and are immobile, while a few small PD units are mounted on grav vehicles.

Invasion: Earth, Rule Book, p. 3

The combat system used in Invasion: Earth is near-identical to FFW. Adjustments for Armor, Elite, and Mercenary units are still here. Tech level differences shift columns on the Troop Combat Table. The major difference between Invasion: Earth and FFW is the introduction of movement rules.

Like FFW before, the rule book for Invasion: Earth includes extensive ideas for integrating the game with a Traveller RPG campaign. Additionally, though Invasion: Earth focuses on one (“historical”) planetary invasion, the end of the rule book also includes a section for taking the rules and using them for other campaigns, including troops not equipped with grav vehicles (the default in IE).

JTAS Articles

JTAS #9 Cover

A review of the first 24 issues of the Journal of the Traveller’s Aid Society reveals only a small handful of articles related to rules for these strategic wargames. Not surprising, in a way, given JTAS was intended to support the Traveller RPG game and not the wargame line of GDW.

JTAS 1 (1979)

This issue contained the article “Diplomacy in Imperium” which introduced a variant using Emissaries into the campaign. Meh.

JTAS 5 (1980)

This cover article in this issue is “Imperium: Ground Combat Module” by the same Roberto Camino that did the “Diplomacy” variant in Issue 1. The ground system he introduces is something between Imperium and Invasion: Earth with planets depicted on two hemispherical maps. This module is intended to replace the Surface Combat phase of Imperium.

JTAS 9 (1981)

This was a “special” Fifth Frontier War edition with lots of background material for the game (some of which was duplicative of the rule book).

What’s the Best Strategy?

As similar as two of these game are, all three of these strategic Traveller wargames offer very different approaches to the Traveller RPG universe. That said, all three of these games are clearly wargames-first and the integration with the Traveller RPG is difficult at best. This is very much unlike almost every Personal/Tactical combat game that is tightly tied to (even forming) the roleplaying game rules.

Imperium is by far the most abstract of the strategic models and unsurprisingly the easiest to learn and play. It also has no expressed technological aspect. Coming before the publication of Traveller, it is also probably the most difficult to “fit” into a Traveller RPG campaign setting as it uses many elements of the setting but in ways that are not directly relatable to the RPG.

Fifth Frontier War, regardless of the “For Use With TRAVELLER” tagline, is a separate wargame set in the Traveller RPG universe. FFW probably does the second-best job of capturing the technological difference of any Traveller wargame, either Personal/Tactical or Strategic. Although there are extensive notes describing how to use FFW in a Traveller RPG campaign, the truth to the matter is the two systems, though set in the same universe and sharing common foundations, are too different in scale to be combined.

Invasion: Earth is the best wargame/RPG system, either Personal/Tactical or Strategic, to capture the impact of technology on ground warfare in the Traveller universe. Like FFW, however, integrating Invasion: Earth into a Traveller RPG campaign is very challenging due once again to the differences in scale. Invasion: Earth is closer to an RPG than FFW, but fighting two weeks of battles between Regiments or Armies is far above the “personal view” that the Traveller RPG is built on.

Interestingly, even though there are more than few articles that discuss integrating the tactical-scale Striker (GDW, 1981) into Traveller campaign, I find no articles or rules about integrating Striker into Imperium, FFW, or Invasion: Earth. I realize Striker was published near-simultaneous to FFW and Invasion: Earth, but you would think even after the fact somebody might had made an attempt in JTAS. Guess not. Once again, the difference in scale is probably just too much to overcome.

*Interestingly, the Traveller Combat System was never called TCS. Within the Traveller rules system, TCS is the abbreviation for “Trillion Credit Squadron.”

One thought on “#Wargame Wednesday – Searching for My Strategic #TravellerRPG Wargame

  1. Excellent: I only own Imperium and Dark Nebula in hard-copy, and since I have a war brewing in my campaign was looking at using one of them to conduct the backdrop parts while interweaving the PC’s actions. Since I have the FFE Traveller CD’s I’ll take a look at Invasion: Earth’s rules for the ground-combat portion of the war. Thanks for the summary review!

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