From Destinypedia, the Destiny wiki
The Cabal are a warmongering race of giant bipedal humanoids with a heavy-set, rhinoceros-like appearance. Their ever expanding interstellar Cabal Empire spreads through organization, efficiency, and corruption. The Cabal army that occupied Mars and held it for some time was but a fraction of their full might. During the Red War, Cabal warlord Dominus Ghaul and his Red Legion seized the Last City and the Traveler in a surprise attack. After Ghaul's demise, the Red Legion shattered into numerous warring factions across the Solar System. The exiled Emperor Calus, previously dethroned by Ghaul and later arriving onboard his spaceship, the Leviathan, presents less antagonistic attitude towards humanity and the Guardians.
The Cabal are an extremely tough species, willing to defend their territory until every last one of them is dead. Their architecture is very industrial, with an emphasis on burrowing into mountains for defense. They are a very industrious, militaristic species whose social structure and way of life revolves largely around conquest and expansion. Their armor and technology can often be seen leaking a substance similar to oil and even emit smoke when damaged or worn. For centuries they have devoted their resources to occupying and mining Mars, contesting with the native Vex programming as evidenced by the many Cabal ships seen bringing armies to and from the red planet, and recently dealing with the Guardians.
Interestingly, the Cabal is the only hostile race up to date that does not appear to overtly feature worship in its culture—the Fallen worship their god-like Servitors, while Hive have devoted their entire religion to the worship of the Darkness, while the Vex of the Sol Divisive revere the unknown entity that is the Black Heart—but as of the Taken War, evidence has been gathered that the Cabal revere a deity-like Emperor, later being revealed to be Emperor Calus. And at one point, they have even ruled the galaxy, and since the reformations that happened within their empire, they seek to do it again, and likely beyond.
According to Cabal myth, the first Emperor was a hero named Acrius who allegedly took the sun. In the earliest days of this new empire, the Cabal emperor ruled alongside the venal military aristocracy known as the Praetorate, which allowed the people to suffer so the Legions who served them could grow.
Rise of Calus
Upon Calus's Inauguration, he had the wasteland of an unknown planet cleared of any stone or plant in order to have a desert of pure white. Three days later, a violet pavilion was constructed and Calus's court was recreated in every detail.  The first act of his coronation was to send the Consul into the wasteland as a symbol for the revolution he would soon bring. During his reign, Calus decided to purge the corrupt Praetorate and he and his imperial guard marched into the temple where the former Cabal senate convened and assassinated them.  He then granted citizenship to the various Legions and set Evocate-General Umun'arath as Primus of All Legions.
During this time, Calus moves the Capital to Torobatl so it could be closer to his people, throwing parades daily as he bought from the local marketplaces. Following his "great purge", Calus spoke to the people at Dau'uss, announcing that he had repossessed the wealth and plunder of the Praetorate elite. 
Calus's reign was not without personal troubles. He was wary of Umun'arath, his Evocate-General, for her paranoia and obsessive fixation on war. His own daughter and heir, Caiatl, grew up similarly despite his efforts.
One of Calus's pleasures was the Coliseum, and one day, an albino gladiator named Ghaul made his first appearance there. Ghaul's patient skill and unusual coloration soon made him a favorite of Calus's, and the Emperor eventually made him Primus of the Red Legion, where his talents would be put to better use. Calus grew to love Ghaul like a son, and believed they were kindred spirits who both envisioned a newer, more perfect world. Ghaul's association with The Consul and members of the Praetorate worried him, but not enough.
Calus claims to have overseen a reign of glory. His Empire was an immense military power, but valued willpower, learning, gentility, and subtlety. Debate was as celebrated as warfare. Savage pit fights coexisted with precise marksmanship and refined martial arts. The Empire crafted technological marvels that allowed every need to be met and every life to be lived in comfort.
As the Cabal Empire expanded, it encountered countless alien races and absorbed them into itself: indoctrinating their species, collecting their technology, learning their knowledge, and merging with their culture. The number of species within the Cabal Empire "defied reckoning," and examples of the things they created, whether texts, tech, or superweapons, were archived in carefully maintained athenaeum worlds for study and potential future use.
Centuries after destroying the Psions' clairvoyant OXA Machine, word reached the emperor that it had been rebuilt on the moon of Brand. The Evocate-General then sent her ships to bomb the moon but Calus stopped her ships and instead proposed an alliance with Otzot, the Psion which rebuilt the machine. 
It was seemingly during Calus's reign that the Cabal learned of the Traveler and the Light, and gained some knowledge on the Darkness from the "Dreams of worms". His Empire has even defeated a Light-empowered race on at least one occasion.
However Ghaul, having grown disillusioned with Calus's reign and determined to return the Cabal to their warmongering ways, conspired with the Consul and several of Calus's closest friends and advisors: Umun'arath, Shayotet, Otzot, Moli Imoli, Iska'al, and Caiatl in a bid to usurp the Emperor. Ghaul and his Red Legion launched his coup in the dead of night, arresting Calus and his Loyalists. With the Emperor too popular to simply execute, Ghaul, his Red Legion, and the Consul sentenced Calus and his supporters to exile aboard the Leviathan, taken far from the Empire along a pre-programmed course.
Ghaul swiftly assumed power. Declaring that there would be no more emperors, he instead assumed the title of Dominus and imposed radical reforms on the Empire. Under his leadership, Cabal culture moved from hedonism and pleasure for all to militarism and personal glory. The Empire's member species were diminished in relevance. Its subtlety was replaced by brute, industrial force. It conquered rather than absorbed.
War for the Sol System
Arrival in the Solar System
The Cabal's scouting legions arrived in the Solar System at some point following the Collapse. Encountering no meaningful opposition, they established a beachhead on Phobos, constructing massive facilities such as Fleetbase Korus and Firebase Thuria before invading Mars. Their initial intention was to mine Mars for resources, but the scope greatly expanded upon discovery of the Vex ruins. The Virgo Prohibiton, the Vex collective on Mars, didn't take too well to the Cabal arrival, and so began a war that wouldn't end until The Red War.
A Ghost that had infiltrated a Cabal base on the planet took note of visible dissent among their ranks: while some remained loyal to the Empire and obeyed their ancient orders without question, others did not, and tensions between the two groups may presage a schism. It is possible that some Cabal were aware of Ghaul's coup against the Emperor, which may have been an additional source of tension, but the transmissions for this do not make it clear whether all of the Martian Cabal knew, or if they had taken any sides. One unit, the Broken Legion commanded by Valus Trau'ug, even mutinied, massacring his superiors and attacking the Reef without authorization, resulting in their capture by the Awoken. For Trau'ug's treason and failure, Cabal High Command disavowed the entire legion, leaving them in the Prison of Elders.
During the Guardians' mission to reach the Black Garden, the Guardians had to charge a Gate Lord's eye to unlock the gateway. Traveling to Mars, the Guardians breached into the Conflux to power the eye but encountered regiments of the Blind Legion, a cabal army tasked with capturing and holding Vex artifacts. Despite the Cabal's efforts, the Guardians were able to reach the main site of the Conflux and begin to charge the eye but are then confronted by the Blind Legion's commander, Primus Sha'aull. After a heated battle and despite the Primus' efforts, the Guardians were able to charge the eye and kill Sha'aull. With the eye fully charged, the Guardians were able to reach the Black Garden. With the Primus dead, the Blind Legion was without a commander; a huge blow, and one in which the Blind Legion would never recover from.
At a later date, the Vanguard received a message from the Warmind Rasputin, warning them that a trio of Psion Flayers, called the Ice Reapers, were attempting to hack its mainframe on Mars, after the Warmind used Warsats to bombard Cabal troops. Wanting to prevent the Cabal from hacking into the Warmind's data and weapon systems, the Guardians formed a strike team and battled with the Cabal through the Dust Palace located in Freehold. Reaching to the Flayers' position, the Guardians made combat with the elite Psions and their guard but despite their power, they succeeded in slaying the Psions, saving Rasputin. A huge blow to another Cabal Legion, and one that seemingly destroyed the Ice Reapers, as they were never seen again.
Wishing to take the fight to the Cabal, the Vanguard saw an opportunity to strike a blow against the Cabal when Valus Ta'aurc, the infamous commander of the Siege Dancers, was seen in his Land Tank, Cerberus Vae III, stationed in the Valley of Kings. Forming a strike team and managing to breach past the Cabal's defenses, the Guardians were able to enter the Land Tank and confront Valus Ta'aurc. After a struggle, the Guardians succeeded in slaying the Valus, dealing a critical blow to the Siege Dancers and Cabal leadership on Mars. Not only did they slay the Valus but they also slew 4 others; ending The Siege Dancers chain of command and knocking them out of the war on Mars, along with the Ice Reapers, out of the fight.
The Taken War
Prior to the start of the Taken War, the Vanguard speculated that a new task force, a "second fleet" led by the Skyburners, was being assembled at Phobos for the purpose of invading Earth. After the arrival of Oryx, the Taken King and his Dreadnaught, however, the Cabal were forced to evacuate their Fleetbase and other sites in the system due to Taken infestations. This was a huge blow. In the ensuing battles, various detachments across Phobos and Mars suffered enormous casualties against the Taken, with the Sand Eaters losing 58% of their troops, the Blind Legion losing 35%, and the Dust Giants losing 39%. In addition, the entire local Cabal fleet was mobilized, and any ship that was not already on the move by the time the Guardian arrived on Phobos was believed to have been destroyed. With the Skyburners being redeployed to reinforce the other battered Cabal during the course of the Taken War, the campaign against Earth was temporarily placed on hold. Following this considerable setback, Primus Ta'aun, commander of the Skyburners and the mightiest Cabal in Sol, sent a report up the Cabal chain of command suggesting that the Hive technology aboard the Dreadnaught could be co-opted for Cabal use. Ta'aun also proposed any technology recovered could be used against Guardians, as the Primus had begun to realize that the Cabal battle strategy was becoming hopelessly mired in a losing attrition war with the City. His report reached Dominus Ghaul, who then ordered Ta'aun to personally board and capture the Hive vessel by any means necessary. In the aftermath of the Battle of Saturn, Ta'aun rammed his warship, the Dantalion Exodus VI, into the Dreadnaught in order to establish a beachhead. While leading a squad through the Mausoleum in an attempt to reach Oryx's ascendant realm, Ta'aun was Taken and transformed into Ta'aun, Hand of Oryx. Ta'aun's bond-brothers Valus Mau'ual and Valus Tlu'urn then ventured deep into the Dreadnaught and planted explosives at its power core, either as part of a preconceived plan to force the Hive's surrender, to avenge their lost Primus, or both. If allowed to succeed, the blast would have destroyed majority of the Solar System. Fortunately, the two Shield Brothers were stopped by a Guardian fireteam before the explosives could be detonated. Their leaders vanquished, the surviving Cabal on Dantalion Exodus VI transmitted a distress signal to the rest of the Empire. Though the Guardian disabled this signal, they were unable to prevent it from reaching its intended recipient. The remaining Skyburners on the Dreadnaught continued to fight a desperate struggle to survive as their beachhead was slowly overrun by Hive and Taken. Eventually, the remaining Skyburners were slaughtered.
Meanwhile, on Mars, the Cabal clashed with the resurgent House of Wolves, who had gathered on the red planet to heed the call of their new God-Servitor Orbiks Prime. Weakened by the casualties suffered in previous conflicts, the Cabal were unable to evict the scavengers as they took the Cabal's subterranean labyrinths for their own. The Guardians solved the problem by destroying the Servitor, leaving the Wolves broken once more.
Shortly after Oryx's defeat, a New Monarchy agent sent a report to his Executor superior which noted the depletion of Cabal leadership: the Skyburners' Primus and his bond-brothers, Primus Sha'aul, Valus Ta'aurc, Valus Trau'ug, and a large mass of lesser Vals and Bracuses all dead or heavily outnumbered. The New Monarchy believed that in the face of such staggering losses, the Cabal Empire would have no choice but to respond to the Guardians' attacks. In due time, the Cabal's response would arrive.
The Red War
Seeking the Light
Two years after the Taken War and one year after the SIVA Crisis The Cabal Empire's response would finally arrive. The Red Legion under the command of Dominus Ghaul who would launch a devastating assault on the Last City which was carried out flawlessly. Taking the City by surprise, the Red Legion rapidly overwhelmed it and destroyed the Tower while his cage device latched onto the Traveler. Ghaul's forces took particular care to capture the Speaker alive, as the Dominus was interested in his connection to the Traveler. In a desperate plan to kill him, The Guardian boarded his flagship, The Immortal, and destroyed its shield generator in advance of a concentrated attack. This attack never materialized, and Ghaul personally stepped out to confront the Guardian. As the two faced off, the Cage activated its suppressive shield and stripped the Guardian -- all Guardians -- of their Light. With his victory assured, Ghaul beat and mocked the Guardian before kicking them off of the Immortal. Dominus Ghaul and his Red Legion had succeeded where previous forces had failed to accomplish for centuries, invading the Last City and defeating its Guardians.
Days later, aboard the Immortal, Ghaul implored the Traveler to choose him and join his empire. The Consul, in contrast, only viewed it as an advanced machine, and advised Ghaul to simply seize its Light by force. Ghaul disagreed with the Consul's approach and had the Speaker brought to him, seeking to use him to gain the Traveler's approval.
In addition to conquering the Last City, he sent his prized warship, The Almighty, to the systems sun to destabilize it and cause it to go supernova should the system resist any further. His remaining forces have been sent to the European Dead Zone to hunt the remaining Guardians, to Io to mine the remaining energy from the Traveler and to Nessus to study the Vex. Ghaul also sent a powerful force to Mars to reinforce the Cabal forces there, finally driving the Vex from Meridian Bay and destroying the portal to the Black Garden, he also destroyed most of the Virgo Prohibition, and all other places in the solar system.
For a time, the Red Legion maintained complete control of the Solar System but a few Guardians were able to regain control of their Light from interacting with a Shard of the Traveler in the European Dead Zone. In doing so, they began to fight back against the Red Legion, humiliating their forces. At first, the guardians conducted minor operations such as scouting and analysis. These operations would soon advance into the theft of Legion supplies, and the assassination of their leaders. Soon after, the Legion firebase is disabled, with further operations being carried out. Gathering the Remnants of the Vanguard, the Guardians planned an organized attack to reclaim the Last City preceded by the disabling of the Almighty. Despite the loss of their Light, the Vanguard Leadership launched the attack to reclaim the Last City. As this occurred, the Guardian was tasked with boarding the Almighty and permanently disabling the superweapon. After eliminating the thread of the Almighty, the Guardian heads back to Earth to join the fight. Hearing of both the attack and the loss of the Almighty, the Consul angrily demanded Ghaul to take the Light from the Traveler, and destroy the Guardians. The Dominus, however, remained adamant that he needed to prove his worth to be chosen by the Traveler. In his rage, the Consul released the weakened Speaker and ranted that Ghaul had already been chosen, not by the Traveler but by the Consul, the day he found him as an orphan and raised him to be the warrior who would deliver their people and promise him vengeance. Convinced by this argument but angered by the Consul's arrogant insubordination, Ghaul killed his old adviser while swearing to take the Light by force.
At the top of his warship near the Traveler's Cage, Ghaul faces off against the Guardian he previously defeated once more, this time infused with some of the Traveler's Light, granting him similar abilities to the Guardians. However, the Light that was bestowed upon him was corrupted. After a fierce battle between the two, Ghaul was eventually defeated. Upon his defeat, Ghaul attempts to use Radiance and is resurrected as a massive ethereal figure due to his corrupted Light, declaring himself immortal as he speaks to the Traveler directly. In doing so, the Traveler wakes from its slumber, destroying the device that was harvesting its power and then destroys Ghaul himself, sending a massive shockwave across the planet and system, restoring the Light and ending Ghaul's threat forever. With their Light restored, the Guardians succeed in reclaiming the City and drove out the Red Legion. For the first time in history, the Red Legion has known true defeat and their seemingly undefeated leader was now dead.
Despite Ghaul's death and the liberation of the Last City, the Red Legion continued to carry on the Red War but had become seriously weakened and demoralized at the loss of their leader. Even so, the Guardians continued to battle with the Red Legion across the System. The Guardians succeeded in thwarting numerous and desperate plots the Cabal planned to give them an advantage, from using Taken energy to strengthen their forces, to destroying Protheon, Modular Mind before they could utilize the Axis Mind as a weapon, and acquiring deadly weapons from Bracus Zahn and his disgraced forces.
The Legion is currently active on Mercury, following Ghaul's death, getting into a stalemate with the Vex. Another remnant of the Red Legion traveled to Mars to resupply its forces but encountered the mysterious Hive army, the Grasp of Nokris. Now the Cabal enter into a stalemate with the Hive for control of Hellas Basin while also dealing with Guardian attacks.
Return of Calus
After the death of Ghaul, the former Emperor of the Cabal, Calus, arrived in the Solar System aboard his massive craft, the Leviathan, and immediately set to work on reclaiming the empire. He gave elements of the leaderless Red Legion the chance to "join the loyalist regime," sending them on missions to collect geological data on Nessus. These transmissions are intercepted in the Adventure Invitation from the Emperor. Calus intended to convert the soil of the planet into "Royal Wine".
Calus extended an invitation to The Guardian to board his vessel for slaying Ghaul. The Guardians accepted Calus' challenge and following a long journey through Calus' palace and defeating his loyalist army, the Guardians seemingly meet Calus in person in his throne room. Facing off against the exiled Cabal Emperor, the Guardians survive his strange powers and after dealing critical damage to him, they found that the Calus they were facing was really a robotic duplicate. Regardless, the Guardians succeed in destroying the robot. Before the destruction of the machine, Calus boasted about his power and claims to know the "real truth" about the galaxy and the purpose of the Traveler. Nonetheless, he rewards the Guardians for completing his challenge and offers them a place by his side should they seek him out.
Some months later, Emperor Calus called upon the Guardians again when his Leviathan broke off a chunk of Nessus that contained a powerful Axis Mind, Argos, Planetary Core, thus clogging up the massive vessel. Instructing them to repair his ship, the Guardians travel through the bowels of the Leviathan and succeed in repairing it and battle with Argos in the fiery maw of the ship. After a perilous struggle against the Axis Mind, the Guardians succeed in disabling its shield and destroy the mind. However, with Argos's shield gone, the Guardians were soon to be devoured by the inferno of the Leviathan. Fortunately, Calus saves the Guardians and rewards them for their success and the Cabal Emperor once again offers them more than just the power of the Light, as Calus demonstrated that he can keep them safe. He also cryptically warns them that the "end" is near and therefore must be ready, as he will find them again.
Rise of Ca'uor
Some time later, following the end of the Red War, in the vacancy that was left behind by Ghaul's death, Val Ca'uor took advantage of the power vacuum and quickly asserted himself as the commander of the Red Legion. Under his direction, he hoped to resupply the Red Legion by pillaging Vex technology from Mercury and gather energy from Mars to regain their strength following the failure to capture the Traveler and defeat the Guardians. However, both efforts led to conflict with the Vex and the newly arisen Hive faction, the Grasp of Nokris respectively.
After Xol, Will of the Thousands was killed, Val Ca'uor led a fleet against The Leviathan in order to kill Emperor Calus and seize the ship for the Red Legion's purposes. His forces occupied the Spire of Stars, inflicting many Loyalist casualties, even destroying one of Calus's robotic duplicates. However, a Guardian team was sent by Calus in response, and with the aid of his psychic powers, they raided the spire, killed many of his troops, commanders and decimated the Red Legion fleet. Ca'uor was finally intercepted at the Celestial Observatory and in the following battle, he was overpowered by the team. Calus is impressed that the Guardians have grown "fat from strength and power" and rewards them once again. Calus then tells the Guardians that he awaits the day they will stand by his side when the end comes.
A Broken Legion
Scattered Across the Sol System
Following their decimating defeat on the Leviathan and the loss of Ca'uor, any remaining survivors of the Red Legion found themselves within the Reef struggling to survive even as the region of space descended into chaos as the Fallen Scorn rampaged across the Awoken's domain. Yet at the same time, they found themselves in between the Guardians personal war with the Scorn, losing causalities to both groups during the conflict.
In addition to their disheveled state, the Red Legion begun suffering from multiple desertions such as those following Garut Gra'am who rooted themselves in Trappers Cave. The most prominent of these groups, the Unbowed Legion, made their debut in the EAZ during the Solstice of Heroes event in an attempt to take over the EAZ as a base of operations. Despite the group being lead by three large Cabal commanders similar to Ghalak the Colossus, Forge Warden, they were quickly put to an end by the Guardians partaking in the event.
In response, the Cabal have made actions against deserters, even placing Wanted Bounties through the Spider, as in the case of Valus Dulurc. Against the deprivation the legion currently faces they have been seen to continue some operations such as an attempt to take over the EAZ lead by two Bond Sisters. Other operations by the Red Legion include multiple attempts to gain territory such as assaulting Lost Sectors across the system and flushing out their inhabitants. Only the Combustor Valus and Blood Cleaver would be successful in this before eventually falling to money-hungry Guardians.
Opulence and Sorrow
Sometime following the Guardians recent battles with the Kell's Scourge and dealings with the Drifter, Emperor Calus called upon the Guardians once more for a challenge that threatens his Leviathan. One of his former Shadows, Gahlran, had gone mad after using the Hive artifact the Crown of Sorrow. It was soon revealed that Calus desired a Shadow to command the Hive and further his goals but Savathûn, the Witch-Queen laid a trap for the Cabal Emperor using the Crown. Though Gahlran was bred to control the artifact to further Calus's goals, he was ultimately consumed by it, which allowed the Hive to infest the deep treasure vaults of the Leviathan.
Wanting to cleanse the infestation and have Gahlran put down before his terror brought calamity, Calus had the Guardians form a Raid team to purge his space craft. The Guardians traversed the treasure vaults and encounter many dangerous Hive rituals but manage to persevere and reach Galhran himself. Despite the Crown granting Gahlran great dark Hive powers, the Guardians managed to slay the Sorrow-bearer, completely purging the Hive from the Leviathan. Calus, pleased with their continued successes, rewards the Guardians with great riches and officially names them one of his Shadows.
The Guardians accession to Shadow became sour news towards some in the Last City, particularly the Warlock Aunor Mahal, who believed that Calus is subverting the Guardians's priorities, brought her concerns and findings to the Vanguard. She proposed that the Last City should storm the Leviathan and take Calus out before his plans come to fruition. Unfortunately for the Praxic Warlock, while the Vanguard acknowledged that Calus was no ally, he kept the Red Legion in check and supplied the Guardians, nor did they wish to start a war with him. They reasoned that in time, Calus's influence over the Guardians will fall and if the Cabal Emperor does make a wrong move, they will not hesitate to send a strike team.
In the meantime, Calus extends an invitation to Eris Morn, offering her the position to replace Gahlran as Shadow of the Hive, knowing of her history with her hated enemies.
Meddling with Time
Sometime after the Guardians' conflicts with the Hive and Nightmares on Luna and defeating the Vex Offensives, Osiris calls upon the Young Wolf to Mercury. The legendary Warlock claims that after The Undying Mind's final destruction, the timeways over Mercury have been undone and worse, a council of Cabal Psion Flayers aim to take advantage of the Vex's disorganization to assume control over time itself and undo their defeat during the Red War. Their meddling with Osiris's time-altering Sundial resulted in Mercury fracturing into three different eras, each with their own timelines dictated by the Psion Flayers. The Guardians team up with Osiris to ensure the safety of time, preserve the present and to save a legend, Saint-14.
The Guardians are successful in saving Saint-14 from his fate but during the three weeks of this conflict, Guardians also manage to slay the Psion Flayer orchestrators; the sisters, Niruul, the Hollow Voice, Ozletc, the Sky Piercer and Tazaroc, the Sun Eater, one by one.
After a few more weeks of combating the Red Legion near the Sundial, the Flayer sisters would band together and use their power to fuse into Inotam, Oblivion's Triune, to finish off the Guardians. Inotam violently clashed with the Guardians for control of the Sundial but despite her vast powers and reinforcements, the Guardians are successful in slaying Inotam, ending the Psion Flayer's schemes to subvert time. Regardless of this victory, Osiris feels that other Red Legion radicals exist and the Guardians must be ready for when they will appear. Osiris would in fact be right, for unknown to the Guardians, a fourth Psion Flayer remains; Amtec, the youngest of the sisters. Having been told of the possibility of her sisters's demise, Amtec now schemes to exact vengeance upon the Guardians in the name of her sisters.
After their crippling defeat at the Sundial, a contingent of the Red Legion, headed by the last remaining Psion Flayer, Amtec, decide to direct the Almighty into an ongoing collision into the Last City itself; disabling its propulsion engines and navigation systems despite the efforts of Zavala and Ana Bray. With little to no choice, the Vanguard decide to cooperate with the Warmind Rasputin, with Guardians arming his arsenal of Warsat satellites, in order to save their home from destruction. A minor assault was staged against the Warmind's core on Mars only to be thwarted by the Guardian and Rasputin's frames. The Legion also has forces engaging the Seraph Towers throughout the system to prevent Rasputin's armaments from destroying the Almighty.
Meanwhile, a Shadow in service of Calus made off with the Fourth Horseman, an infamous Cabal killer stolen from the Tower, to eliminate key Red Legionnaires. However, the agent was disposed by a countermeasure put into place by Emperor Calus’s daughter, the Imperial Princess Caiatl. Regardless of this countermeasure, the Guardians were successful in reclaiming the Fourth Horsemen from a company of Red Legion soldiers guarding it.
During the past few months as Guardians succeeded in activating Rasputin's Seraph Bunkers, The Almighty had almost reached the Last City, so close, it could be seen from the Tower. Thankfully, Rasputin used his re-activated armaments and destroyed the Almighty, finally ending the Red Legion’s plot to annihilate the City, as well as destroying one of Ghaul’s most finest and destructive works. While the remains of the legendary sun destroyer plummeted into mountains close by with a small chunk chipping off a piece of the Tower, the Guardian's home was saved and the Cabal's latest scheme had been reduced to ruble. It is unknown if Amtec died on the ship or not.
With the Almighty's crash site no longer inflame and its debris no longer falling from the sky, the Red Legion was reduced to a barren few after countless losses. Despite this, the Legion still operates. Several groups of Cabal interfered with the Guardian efforts to collect energy from Pyramid scout ships on Io, seeking to take the phantasmal energy being gathered for their own unknown uses under the leadership of many Champions. These Champions have been seen to collect blooms, concentrated amounts of phantasmal energy from pyramid scales, and secure them for extraction. It is also unknown whether or not Amtec still leads the remains of the Legion due to her possible death on the Almighty remains unconfirmed. With their current state, it is possible they could turn to either Calus' Loyalists or, more likely, Caiatl's Regime. From what is learned by the Guardians at the Tree of Silver Wings, it is extremely likely the Darkness speaks/has spoken to the Cabal.
In the wake of many destinations vanishing, Xivu Arath's Cryptoliths began corrupting many Red Legion Cabal just as Caiatl was beginning to rally the remaining remnants of the Legion through both the use of encrypted communications and blue emissaries. Entire encampments were abandoned along with mass graves reported and entire groups slaughtering each other or suffering internal conflict due to the Cryptoliths' influence leading Caiatl and her Scouts to become weary and attempt to investigate the situation.
Around the same time, Calus, the Loyalists, and the Leviathan mysteriously vanished from the orbit of Nessus. Osiris looked into its disappearance but found nothing hinting as to why the Leviathan left or where it was headed.
While the Cabal are a militaristic species with a penchant for conquest, as evident by the existence of the Psion client race, their exact motivation for coming to the Solar System is unclear. They have a fascination with the Vex and their technology, as evidenced by their heavy presence at numerous Vex sites across Mars, such as the gate to the Black Garden and the spire that unlocks it. The Cabal also sent an expedition to Mercury to investigate a Vex structure known as Vertigo, but the members of the expedition disappeared under mysterious circumstances without a trace. It is unknown if the Cabal have attempted to visit any other worlds apart from Mercury, Mars, Io and Nessus.
When a Cabal army goes to war it is exiled from the Empire, and is not permitted to return unless victory is secured. This presumably provides Cabal troops with the incentive and motivation needed to endure long-term campaigns, though they can still wear down eventually. Those on Mars showed signs of exhaustion as they were forced to fend off endless Vex assaults in addition to devastating Guardian strikes.
Given the numerous casualties suffered at the hands of the Guardians, the Cabal have set their sights on the City, looking to find ways of neutralizing their self-resurrection abilities before committing to war. Psion Flayers have been indicated to have already analyzed certain areas where Guardians cannot self-resurrect, such as the vicinity of the Black Garden, and that the Hive on the Dreadnaught possess the means of extending these areas. They are capable of very extreme tactics in the name of the Empire; from blowing up entire planets for being in the way, to blowing up most of the system. Cayde-6 considers the Cabal to be war criminals for their brutality. Yet, for all their ferocity, it has been noted that the Cabal seem to secretly be running away from something terrifyingly powerful - possibly the Darkness. The Cabal, under the Red Legion, finally managed to find a way to disable Guardians' self-resurrection abilities through the Traveler Cage but it was later destroyed by the Traveler.
The Cabal's primary reason for coming to Mars was apparently to mine its resources and investigate human technology. This changed with the discovery of the Virgo Prohibition and later the Guardians. Even when the Red Legion arrived, the Cabal still displayed an interest in mining.
The Cabal are a bipedal, hulking species that appear to be carnivorous, as evidenced by their many sharp, irregular teeth. They have wrinkled, leathery tan-grey skin, a tall skull, dark wide-set eyes with slit pupils, and a very high, inverted-V-shaped upper lip that exposes the Cabal's upper gums and fangs. They come from a warm, humid climate, so they have to be constantly hydrated within their suits. Therefore, while a resilient species, Cabal cannot survive in Mars's blistering environment without climate-controlled gel suits. Cabal have long lifespans, in one case having lived well over a thousand years without any apparent infirmity.
The Cabal species has male and female sexes, and presumably reproduces sexually. The Cabal have advanced cloning and genetic manipulation technology, as exemplified by the Ceremonial Bathers spawned by the Leviathan's cloning facilities. 
References in the Grimoire indicate that the Cabal have females serving in their rank and file. However, they are indistinguishable from the males in gameplay, making the Cabal seem androgynous in human eyes. Depictions of two known female Cabal, Caiatl and Umun'arath, suggest that they have tusks, while males do not. Recordings from the Councillor Match suggest that young female Cabal get 'first tusks', perhaps implying that these can be shed like the antlers on a deer. This is supported by certain unique Cabal enemies such as the European Aerial Zone Bond Sisters, who lack tusks but are confirmed to be female.
The Drifter claims that Cabal do not have any fat on their bodies, only muscle.
The Cabal language is Ulurant. It has been described as "grunting" and "moronic", lacking in subtlety.  Nevertheless, the City has yet to fully translate it or its various dialects.  The Cabal are confused by the term "Ghost", translating it as "Dead Person",  though this may be a simple error in semantics as the word "ghost" indeed exists in the Cabal vocabulary.  They do not appear to have a word for "hubris"  or "retreat" ; conversely, they have six words for "advance". In the Warmind comic, it is written using a heavily distorted English alphabet, with each word flipped upside down and reversed. When speaking to Uldren Sov in the Black Garden, a legionary's speech is transcribed with the tone of a stereotypical London accent.
Like humans, Cabal make use of the decimal, or base-ten numeral system. A system similar to Roman numerals also appears to be in use, primarily seen in the naming of heavy vehicles such as the Cerberus Vae III or the Dantalion Exodus VI.
Research and Development
The Cabal are always looking for ways to increase their power, and have devoted a lot of time to finding and adapting the technology of other races. However, they frequently do not fully develop the technologies they use, leaving structural weaknesses to be exploited, as Ikora notes in Reversing the Polarity. Ghost also noted on Mars that their security systems are absurdly easy to exploit, claiming they were less complex than DOS, which is a family of basic operating systems that were antiquated even before the human Golden Age. A poor imitation of a Vex device was also found in the Cabal base on Io. They also frequently tamper with forces they hardly understand, whether it's the Traveler's Light, the Taken's radiation, or the Darkness itself.
The Cabal in the Solar System are but one arm of a vast interstellar Empire, and in the words of Valus Tlu'urn are "a few scout legions bogged down in attrition war". The nature of the upper echelons of Cabal leadership, including the identity of the leader of the Cabal in the Solar System, is unknown, except for the fact that the Cabal as a whole are ruled by Dominus Ghaul, who has final authority over military decisions. The Praetorate is an influential military aristocracy that controlled the Empire's Legions in the past, but holds somewhat less power under the reign of Ghaul.
Various military ranks appear among the identified Cabal leaders:
Titles such as Emperor and Consul are used by the Empire's political leaders. Calus held the title of Emperor before his exile. However, upon conquering the Empire, Dominus Ghaul refused to claim the title after he overthrew Calus, insisting that there would be no more Emperors, though his supporters sometimes refer to him as "the Emperor" anyway out of respect.
The Legions themselves are organized into smaller sub-units:
Some Cohorts may have Auxiliary units attached, such as a noncombatant Strategic Intelligence Maniple.
The Red Legion appears to use an alternate command structure with eccentric designations: it is divided into Fractures, which are further subdivided into Scales, Bridges, and Masses. Companies have also been identified, though how they fit into the previous is unclear. 
The Cabal seem to be great architects, they build massive structures and build them within a short period of time depending on the legion. The Red Legion built Firebase Hades in a short period of time without being detected, but this fast building might explain the weaknesses within the Cabal Structures. There structures often have weaknesses that can be exploited. Most of them are impressive however, sloppy in build. They are easy to breach, and are able to be shutdown or disabled for long periods of time (Ex: Firebase Hades which is currently disabled).
Named Individuals and Mini-bosses
Cabal Empire Leadership
Solar System Leadership
In addition to the Cabal themselves, the Cabal Empire includes numerous other species whose civilizations were incorporated into the Empire as clients, either willingly or by force. Several of these were part of the Empire before Calus was ousted during the Midnight Coup, while others were encountered by Calus during his exile and joined his Loyalists faction.
The Cabal rely upon a thick, black, oil-like substance to fuel and supplement much of their technology. It is composed of many unidentified chemicals, and is potentially toxic to non-Cabal. They possess technology, or potentially individuals which enable them to shape and transform the features of planetoids, much like the Hive, but not on the level of the Traveler. This technology has been used by them to draw Mars's moon, Phobos, very close to the planet. They are capable of engineering on enormous scales, as demonstrated by the Traveler Cage, the Almighty, and the Leviathan, and routinely destroy planets for fuel or simply for "getting in the way."  Through the Traveler Cage, they demonstrate the ability to manipulate Light via technological means, and can even forcibly bestow it on beings not originally blessed by the Traveler.
List of appearances