BLUF – Game mechanics are deceptively simple but through play one discovers it’s not necessarily combat that is important but executing an invasion plan that requires proper logistical planning and bringing the right forces to bear at the right time and place versus a stubborn defense that must know when to ‘hide’ and fight another day.
NOW THAT I ACQUIRED A GRAIL WARGAME IN THE TRAVELLER RPG UNIVERSE, it was time to play it. Invasion: Earth – The Final Battle of the Solomani Rim War (GDW, 1981) takes place in the Third Imperium setting of the Classic Traveller RPG. The game depicts the invasion of Earth (Sol) by the Third Imperium in the year 1002 (the 55th or 56th Century compared to today). Interestingly, Invasion: Earth (IE) is a ‘historical’ game in the Traveller RPG line as the invasion takes place just over 100 years in the past of the default setting (years 1105-1107).
Physically, Invasion: Earth is a small game more suited to a folio than a box. The map is small, 16″x21″, which covers not only Sol but also holding boxes for different space locations as well as the terrain key. The game includes 480 counters although half are game markers leaving only 240 pieces for actual combatants. Yes, the counters are small – 1/2″ sized – and challenging to this grognard’s eyes. This is a game where a magnifying glass and tweezers to move stacks is required!
The rule book is just as small – 16 pages – and I previously talked about what I like about it. Although Invasion: Earth is both a space battle and ground combat game, a scenario will see mostly ground combat. As I played my first game of Invasion: Earth I discovered the game proceeded in noticeable ‘phases’ where the players face different challenges and are forced to make sometimes painful decisions.
Phase I – The Space Battle
The Imperial player starts in the Out-System Box and has to ‘jump’ into the Sol System. The arrival area is known as Deep Space. Since the Solomani ships cannot ‘jump’ the Out-System Box effectively serves as the ‘off-map’ assembly area for the Imperial player. The Solomani player cannot set up in Deep Space but instead is limited to Far Orbit (which includes Luna) and Close Orbit – the only orbit which interfaces with the planet. In Phase I the Imperial player has to push aside the Solomani space forces to get to Close Orbit and land troops on the planet.
The problem is those pesky Solomani ships and boats. All ships and boats (non-FTL capable ships) have three ratings – Attack Factor / Bombardment Factor / Defense Factor. However, using the right ship/boat in the right space combat is important. In combat against starships you use the Attack Factor. Combat against boats and ground units use the Bombardment Factor. Each has its own Combat Resolution Table (CRT) where losses are expressed in ‘hits’ or Defense Factors that must be eliminated. This means the first decision the Imperial player faces is how to divide his force to attack defending ships and boats because each squadron can only attack one or the other. Space Combat continues until one side is eliminated or disengages. Ships that disengage move the the Deep Space box where they go into ‘hiding.’ Additionally, if there are no Imperial ships in Close Orbit, those pesky System Defense Boats (SDB) can hide in the ocean. Hidden units have advantages later during the actual Invasion and Occupation phases of the game.
Phase II – Advance Base
For the Imperial player, movement to/from the Out-System can only happen once a turn. This means to bring reinforcements from the Out-System effectively takes two turns. However, if the Imperial player lands a Base on Luna, it becomes an advanced staging area. The challenge for the Imperial player is balancing a need to invade Sol and consolidate forces on Luna. Sounds easy until you take into account Transport.
Different space units have different transport capacities. Ground units have different strength based on their size. Generally speaking, an army is 5C (500), a corps 1C (100), a division 20, a brigade 10, and a regiment 5. Bases (supply points for the Imperial player) are the equivalent of 1C. Different ships can transport different ground units; an Assault Carrier (AR) can carry 6C, a Battle Squadron (BR) carries 20, and a Cruiser Squadron (CR) carries 5. Each ground unit must be carried by a single naval unit – there is no combining 4x CR to carry that 20-Factor division. So the Imperial player has to figure out the logistics game of what ground unit is carried by what squadron. This challenge is not only present in this Advance Base Phase but throughout the game. It becomes even more challenging after Turn 2 when two of the four AR in the game are withdrawn.
Phase III – Invasion!
The invasion of Sol can take place in parallel with the consolidation of an advance base; indeed, the Imperial player is almost forced to execute these two in tandem given the need to achieve victory in the least amount of time. In Invasion: Earth there is little differentiation between ground units but the few differences there are make a big difference.
When landing, eligible defenders roll on the Surface Bombardment Table to see what percentage of the landing attackers are destroyed. The defender totals their Bombardment Factors and rolls single d6 on the column that is closest to, but not more than, that value. The roll is modified by two qualities of the attacker – Tech Level and unit type.
Tech Level (TL) is a key concept in the Traveller RPG setting. The higher the TL the more advanced the unit is. TL is one of the most important factors in combat (more on that later) but in an orbital assault units of a lower TL have a -1 DM to the defenders attack roll, meaning they are likely to suffer MORE casualties. Unit type also plays an important roll. Performing an orbital assault with a unit other than a Jump Troop or Marine is a -3 DM (!). The last thing an attacker from orbit wants to do is land a low-tech, non-Jump or Marine unit against a determined enemy! This means the Imperial player should try to lead the orbital assault with those (few) Jump or Marine troops – assuming they are available and loaded properly on the lead wave.
Phase IV – Occupation
Assuming the Imperial player is able to land troops, in order to win they must control, through occupation, all but 10 Urban hexes on Sol. Control of an Urban hex is through Garrisons. To Garrison a hex it must be either occupied solely by an Imperial unit or within the Zone of Control (ZoC) of an proper Imperial unit and NOT in the ZoC of a Solomani unit. In practice this means the Imperial player will have to slog through many Solomani defenders. To do so will require a thorough understanding of Supply, what makes units different from one another, and Replacements.
Supply for the Solomani player is easy – any Urban or Starport hex is a source of Supply. The Imperial player on the other hand must bring their own supply with them in the form of Bases – that cost 1C to transport – meaning only the (few) AR can deliver them to the surface. Bases also make great targets for the Solomani player. Units that start the turn out of supply may not attack and can defend with half their current value.
At first glance, the ground combat system looks rather like a Lanchester Attrition Model that Trevor Dupuy would be proud of. Combat is a simple odds roll with results expressed in Percentage Loss. The stacking rules allow up to 1000 factors (!!!) in a single hex. So why would one want to play this uninteresting attrition game?
Well, because of the few unit types and Tech Level.
There might not be many different ground units in the game, but the few differences are very important:
- Army, Corps, and Planetary Defense units ONLY extend a ZoC
- Armor units have their strength doubled in attack or defense
- Elite units have their strength doubled (this can stack with the Armor bonus)
- Tech Level differences are COLUMN SHIFTS on the CRT
- Mercenaries with over 50% losses have their attack strength halved (they are in it only for the money)
- Commando units ignore enemy units and ZoC during movement and are always in Supply making them the ultimate infiltrators
- Guerrilla units are attacked with a +3 DM when hiding.
In keeping with a core tenet of the Traveller RPG the greater the TL difference the more the hurt! Assume a TL14 Imperial Elite Tank Division (20-14) is attacking a defending TL11 Solomani Infantry Corps (1C-11) as shown above.
- Imperial attack 20×2 (Armor) x2 (Elite) = 80 vs 100 (1:1.5 SHIFTED UP 3 columns to 2:1) – 8 in 11 chance of 10-70% losses
- Solomani defend 100 vs 80 (1:1 SHIFTED DOWN 3 columns to 1:3) – 3 in 11 chance of 10-20% losses.
At the end of each calendar quarter, a special turn is executed. This is where both sides can receive Replacements in the form of Replacement Points (RP).
- Solomani – Accumulate 1x RP for each ungarrisoned Urban hex on the map (there are 61 Urban hexes at the start)
- Imperial – RP comes in the form of a Wave of 100 RP.
Each RP can rebuild a single ground unit combat factor. It takes 100 RP for the Imperial player to build a Base. The Imperial player can also use a Wave to replace any three eliminated naval units. The Solomani player can start to rebuild an SDB unit at a Starport for no RP but it will not be completed until the next quarter’s special turn (assuming it was not destroyed by being overrun or bombarded). There are additional rules for Emergency Replacements which can be called upon outside of the special turns but are not as plentiful.
End State – Victory
Victory in Invasion: Earth is not based on playing a set number of turns. Instead, in each end of quarter special turn Victory is checked. The Imperial player always has the option of abandoning the invasion which awards the Solomani player a Major Victory. If not, play continues every quarter until the Solomani have 10 or fewer Urban hexes ungarrisoned by the Imperial player. At this point, the Imperial player is awarded 10 VP. Modifiers are then applied:
- -1 VP for each quarter of the invasion
- -1 for each Replacement Wave taken by the Imperial player
- +1 if all Solomani surface units eliminated
- +1 if all Solomani naval units eliminated.
The Level of Victory Table is then consulted:
- VP 7+ > Imperial Decisive Victory
- VP 4-6 > Imperial Major Victory
- VP 1-3 > Imperial Marginal Victory
- VP 0 or -1 > Draw
- VP -2 or -3 > Solomani Marginal Victory
- VP -4 or less > Solomani Major Victory
In order to win, the Imperial player must be both quick AND efficient with their resources; making as much as they can with the assets they have on hand. The Solomani player benefits from a long, drawn out war of attrition and hiding some units to prevent their destruction (a Fleet-in-Being?).
In my game, the Imperial player did not achieve the Standard Victory (10 VP) until the fifth quarter of play (-5 VP). The Imperial player also took 3x Wave of RP (-3 VP). Not all Solomani ground forces were eliminated and there was a lone Solomani CR that hid in Deep Space the entire game . This was enough for an Imperial Marginal Victory – and boy did it feel marginal!
AAR – or – After Action Reaction
Invasion: Earth turns out to not be the game I was expecting. Looking at the box and the first pass through the rules thought I saw a somewhat staid game with a very old-fashioned combat model that didn’t look like a vision of the future but rather a rehash of the past. Instead, what IE delivers is a master-class lesson on opposed landings and shows a vision of the future where timeless lessons of amphibious landings are applied to orbital assaults. The rules drive the players to carefully husbanding their resources and allocating forces with thought. Indeed, I had not expected a game that appears this simple to be this deep in the decisions it forces upon players.
I note that Invasion: Earth was published in 1981, a year before the 1982 Falklands War where the Royal Navy and British ground forces were challenged to figure out how to carefully load troops and logistics on few amphibious ships and execute an amphibious landing far away from their bases. The British also faced a narrow timeline for action being called upon to invade and retake the islands before the winter.* Invasion: Earth and the Falklands War are eerily similar, and even more eery when one considers IE came before the Falklands War. Then again, maybe designers Marc Miller and Frank Chadwick were just expressing age-old, never-changing lessons of amphibious warfare in this paper time machine.
If so they did a very good job.
*For a good modern wargame on the Falklands War that is soloable, I recommend Mrs. Thatchers War from White Dog Games.
Rocky Mountain Navy Gamer 
Excellent feature and congrats on bagging a classic GDW game!