Why are the Cabal in our solar system? This has remained an unanswered question for many lore theorists. The Hive are chasing the Traveler and its Light; Fallen want the Great Machine to return to them; The Vex are trying to insert themselves into space and time; what is the Cabal’s motive for being here?
It’s suggested that they are running from something, fleeing perhaps. My theory is that the Cabal came to our system to mine resources to aid their efforts, whatever they might be.
Let’s start with some actual in-lore connections.
GHOST: There's a notification from three days ago. A "Primus Ta'aun" suspended all Phobos mining operations and recon pending investigation of a trans-Jovian threat.
The Trans-jovian threat is the Dreadnaught entering the system. Notice the mention of mining operations.
GHOST: Cabal mining sites across Mars and Phobos have been hit. Losses to Blind Legion: 35%, Losses to Sand Eaters: 58%, Dust Giants: 39%. What is this?
The wording is important. It’s the mining sites, not the detachments, that have taken losses. If the emphasis was on their presence, wouldn’t they use words like “the Cabal detachment at Rubicon firebase”Instead of focusing on the mining sites?
I believe that whatever the Cabal are after, or were initially after, was based on these mining missions. This is the core of the campaign that brought them to our system, or at least, it was. Their arrival in our system is a mystery. There wasn’t any great battle where the Last City repelled the Cabal. Instead they seem to be concentrated on Mars and its moons. Aside from some Cabal corpses on the Cauldron crucible map, there is very little evidence that they tried to expand further.
We know that Mars is special because of the presence of Relic Iron. It’s described as an extraordinary post-collapse material. Relic Iron also responds to Void forces, which is outlined in the Darkdrinker questline. Foundries on Earth use the material for armor and heavy weapon ammunition. Even rarer is the Relic Crystal found in deposits of Relic Iron. It’s what we use to make the Darkdrinker. Relic Iron is also the inspiration for Dr Willa Bray to develop the first engram matter encryption. To further distinguish Mars from other planets when it comes to special resources, there is mention in the lore of some ancient machine that produces what’s called the “Olympus Tears”. These are tiny cytomachines that attach to powerful Cabal and Vex. Perhaps these could be a reason for the Cabal as well?
So I speculate that this could be the material, or a material close to what the Cabal are after. Look at the Cabal Shield, it’s nearly indestructible, and Relic Iron could be a good source for that protection.
But the Cabal seems to have shifted their objective. Two events following their arrival could have shifted their focus. First, the Cabal engaged the Vex which made them focus on gathering intelligence on this mysterious machine race. And then, the arrival of Guardians on Mars. These indications of the future can be found
The Skyburner fleet has yet to be deployed against the City, bringing Zavala the fear that the Cabal have yet to launch their core campaign.
The Beyond the Sky questline for Warlocks reads
"Thralls beyond number are gathering between the stars. Vast armies of Cabal plan to break our Walls. Our enemies share one advantage over us: numbers. The Vanguard is a Light in the Darkness. And our Light makes us a target. And we must be ready for what comes for us." —Ikora Rey
My theory is that the Cabal initially entered our system as a mining operation, but encounters with Guardians on Mars shifted their focus. To the Cabal, we are the greatest threat to their operations. My theory is that this wasn’t always the objective. If our planet was the main objective, it strikes me as odd that the Cabal didn’t simply go directly to Earth when the city was in its early stages. The Dark Age left us in ruins, and striking before we could organize ourselves makes more sense from a strategic viewpoint. The city grew from rubble, so it’s unlikely to me that the Cabal stopped themselves from attacking because of the Risen. It seems like they were unaware of our presence and capabilities before we tried to break through their Exclusion Zone. They would have already known about our Ghosts, or as they call them, “Dead persons”, if they had scouted Earth.
The most logical conclusion for me is that they did not come to our system to invade Earth but this became their objective once we began to venture out into the system again.
The Cabal arrived in our system with their sights set on Mars. They arrived on Mars and then they discovered the Vex and their interest shifted towards them. The Cabal managed to enter the Vex thought mesh at the Black Garden Gate, and have been gathering intelligence ever since. This is the most logical escalation of the Mars operations.
Then, Guardians arrived, and again the focus of the Cabal shifted. We became the ultimate threat to the Cabal, to the point that they assault the Dreadnaught in order to capture Hive leaders to try to obtain the “secrets” that the Hive use to kill us. The addition of the Cabal centurion and the Psion Flayers to the Challenge of Elders featured the room with piles of dead Ghosts. I think this is to show the Cabal focus on trying to understand how to kill a Guardian, as depicted in the intelligence briefing in the Ghost fragment Cabal 4 card:
Flayer analysis suggests that the Hive have developed unconventional counter-Dead Person capability. The capture of Hive leadership might yield vital strategic intelligence, including weapons or tactics capable of defeating Guardians permanently.
Also, the Cabal champions card:
In short, I believe your supposition is correct. The Empire will have no choice but to respond.
My thinking is that the Cabal are now focused on us, and the Last City. This makes sense with the whole “Cabal have no word for retreat” quote, because the logical response to us killing them on Mars is to try to go for the source of our power, the Ghosts and what seems to be the source for Light in our system, the Traveler. Again, not a theory supported by direct lore points, but it’s the most logical conclusion for me.
I don’t think they came here to escape Oryx either. It doesn’t make sense to send a detachment here to escape Oryx, it would be a much larger fleet if they were indeed trying to escape. They decide to attack the Dreadnaught when they realize the answer to killing Guardians might come from capturing Hive Leaders, not to protect themselves from Oryx. I know a Ghost speculates that they are running from something that might follow them, but then the Emperor orders them to board the Dreadnaught. If you fear it, you don’t send a small detachment to capture it. I think it’s something else, a dying world perhaps.