The region of reality known as subspace has long been dominated by the Shivans--a ruthlessly xenophobic species who consider themselves the arbiters of subspace travel. For millions of years they have successfully crushed those who trespass that domain, much similar to a 15th century pirate armada controlling the trade routes of an ocean.
In specific, the Shivan success has hinged on how opposing species never have either the weaponry to break Shivan shields, or the shields to resist Shivan weapons. Thus the xenophobes scour the universe with multiple clones of the same basic fleet--a swarm of shielded fighters plus bombers, several dozen unshielded frigates, cruisers, and a handful of carrier/destroyers, and then at last a shielded superdestroyer flagship with beam cannons. As these "Lucifer fleets" always win, the Shivans never see reason to upgrade.
The Ancients begin using subspace to expand their empire, thereby eliciting the attention of the Shivans. Like many species prior, the Ancients are unable to counter the resultant onslaught. They do discover how to track Shivan ships into subspace, and likewise find out how even Lucifer-level shielding is useless therein, yet they fail to capitalise on these developments before the eradication of their empire.
Eventually, the Shivans encounter a worthy opponent for the first time: the Guan-di. The new species is not only quick to duplicate Shivan weapons and shields, but also smart enough to develop subspace-tracking technology. Warfare between the two sides forces the loss of many Lucifer fleets, compelling the Shivans to finally change methodology from offense/defense to offense-only. Eliminating shields on all but their fighters and bombers, they arrange beam cannons onto the forward arcs of every large ship. This evolution leads to many beam-laden juggernauts, as the pinnacle of a tactic to overwhelm Guan-di ships as quickly as possible.
Despite that change, however, the Shivan defeats continue to mount. Their efforts are hampered by a reliance on nebula gas for construction, without which their ships simply die faster than replacements can be built. However, Shivan investigations soon reveal that the massive subspace engines of their juggernauts make stars unstable. Subsequent experiments uncover a method to emulate, amplify, and focus that effect so as to detonate a star on command, creating a crude imitation of a nebula.
This finding allows the Shivans to increase production tenfold, and thereby retake the momentum of the war. Yet before long, the Guan-di once again display an adaptive genius by copying the nebula tactic, and thus keeping stride in the arms race. In due course the two sides reach equal footing, where a stagnation of their war for several millennia is the result.
Terran-Vasudan Era, Great War
The Terrans begin exploring their galaxy using subspace, whereby they encounter the Vasudans. Underneath the mutual hostilities and an eventual outbreak of war between the two sides, Galactic Terran Intelligence finds evidence of prior Shivan presence left over from the Ancients' Era. The GTI moves quickly to control the evidence and begin experimentation. Meanwhile, the T-V conflict draws the attention of an obsolete Lucifer fleet on patrol near the bounds of Shivan space; the fleet sets course for the Ross 128 star system and the unstable subspace node thereof.
On arrival, the Shivans begin what they assume will be yet another simple campaign of extermination. Yet the Terrans and Vasudans present a surprise, first by forming an alliance and then by rapidly assimilating Shivan technology--the latter boosted by some of the GTI's prior experiments being smuggled into GTVA efforts. Once again the Shivans find themselves facing a persistent foe, but with the Guan-di war at hand they refuse to commit fully on a two-front fight. Despite the lack of support, as well as a growing GTVA ability to counter Shivan fighters, bombers, and ships-of-the-line, the Lucifer fleet still pushes rapidly forth behind its impervious superdestroyer.
The war next hits climax when the GTVA stumbles upon the Ancients' subspace tracking technology, and the concurrent uselessness of Shivan shields when in transit. With that information, a last-ditch GTVA assault is able to halt the Lucifer fleet before it can reach the Terran homeworld. The subspace node collapses from the superdestroyer's explosion, bringing victory at a price of all contact lost with Terra. Afterward, the remaining Shivans are helpless to resist GTVA mop-up operations, and a tentative peacetime begins.
Terran-Vasudan Era, Post-Great War
Throughout the entire Great War, Galactic Terran Intelligence operatives constantly scavenged the battlefields for items and intel to accelerate the pace of their experiments. In the war's aftermath, GTI forces accumulate sufficient resources to break away entirely from the GTVA. This results in a civil war between the two factions, culminating in the total slaughter of the GTI and the destruction of their project's crown jewel--a superdestroyer based on Shivan technology.
After that victory, the GTVA appropriates some GTI research--especially in regard to Shivan beam weapons--then either destroys or classifies the rest. Later, the kept technologies become part of a joint Terran-Vasudan project to create a juggernaut worthy against any future Shivan superdestroyer fleets. Meanwhile, GTVA officer Aken Bosch undertakes a personal mission to follow in the GTI's footsteps for a different purpose: the establishment of contact with the Shivans.
Terran-Vasudan Era, Second Great War
More than thirty years after their victory over the Shivans, GTVA forces are entangled anew. Humans with anti-Vasudan sentiments have formed a rebel group called the Neo-Terran Front, and are determined to topple the Terran-Vasudan alliance. Unknown to the NTF at large, their supreme commander and the catalyst of the war--Aken Bosch--is in fact using each battle as a cover, so that he can plunder various star systems for Shivan and GTI remnants.
The result of Bosch's efforts is twofold: a device to communicate with the Shivans, plus the finding of a huge subspace gate leftover from the Ancients' empire. One of his ships is dispatched to activate that gate and explore beyond it. Still in full clash versus Guan-di resistance, the Shivans have yet to regain any interest for T-V space. The opening of the gate by Bosch's followers breaks that inattention and draws a few Shivan fighter patrols, leading to the severe damage of the NTF ship.
Oblivious to the above, the GTVA and NTF continue their conflict. However, GTVA investigations do reach the subspace gate, then the derelict ship of Bosch's followers, and finally a group of Shivan reinforcements sent to finish the earlier fight. This encounter leads the GTVA to think a new offensive is near, while in truth they are still viewed by the Shivans as a minor distraction from the Guan-di threat.
Finally, the GTVA is victorious against the NTF. In the last battle, Bosch sacrifices most of his fleet in an effort to make contact with the Shivans. The resultant dialogue is successful from his POV, but in fact the xenophobic species not only considers his communications to be a heresy, they are also angry at the risk of his signals reaching the Guan-di. The Shivans let Bosch believe that a rendezvous will be friendly, whereas their intentions are actually to seize his device for study and take him away for punishment. Likewise they begin shifting several fleets to preemptively establish a foothold in T-V space against the Guan-di.
With the NTF defeated, GTVA focus turns to establishing a defense against the Shivans, in the rising belief that the latter's aggressiveness means another invasion. Soon forced to retreat, the GTVA tries to curb the threat by destroying the subspace gate, only to discover that the node itself does not close. Further combat appears to stop the Shivan incursion at the Capella star system, but the reality is that the Shivans are elsewhere organising supply elements for an armada.
Meanwhile, Aken Bosch and his remaining NTF loyalists finally have their audience with the Shivans, only to get the opposite of what was expected since he and his elite are captured and his crew slaughtered. Yet by a quirk of fate the Shivans do not realise that the device they wanted to study is still onboard his ship, thus they leave it behind. The GTVA remains one step behind the entire scenario, recovering the ship and just enough info to be even more confused about Bosch's motives and the Shivans' behaviour.
Upon confirmation of the Guan-di's imminent arrival, the Shivans quicken their logistical and strategic efforts. From observing those moves, the Terrans and Vasudans get a terrible wake-up call on the extent of Shivan military superiority, although they remain blind to the actual reasons behind the deployments. Evacuations begin out of Capella, and the GTVA fleet offers escort along with plans to box the Shivans into the star system by collapsing its nodes to T-V space.
Mostly ignoring all GTVA activities, the Shivans start massing juggernauts around the Capellan binary, preparing to detonate one of the stars and create a resource nebula. At the same time two GTVA destroyers carry superexplosives into the targeted subspace nodes. Both sides accomplish their goals: the nodes are closed and the star goes nova, thereby halting the Second Great War. While the Shivans now brace on a new front versus the Guan-di, an ignorant GTVA assumes that a reprieve has been won.
The Era of Freespace 3
Almost twenty years after the events of the Second Great War, the GTVA have learned how to replicate the huge subspace gates used by the Ancients. A gate is made and it successfully re-opens the collapsed node to Sol, thus ending a fifty-year divide between Terra and the rest of the GTVA.
Upon that reunion, however, surprises unfold: a rebuilt GTI at Terra has spent the time using wreckage from the Shivan superdestroyer to inform the creation of a new Terran / Vasudan / Shivan juggernaut, the Olympus Mons. Not only does the ship own a pair of super beam cannon six times stronger than any prior, its makers also developed a shield system impervious to lesser beams yet still slightly protective in subspace. The GTI / GTVA forces combine to plan for more warships, as well as to upgrade the existing GTVA fleet.
On the edge of T-V space, warfare between the Shivans and the Guan-di is running full tilt, where neither has an advantage and both are wrestling over nearby subspace nodes. Their tumult spills over near the Ross 128 star system, where an unstable node now becomes stable and allows transit for fleets of titanic ships and innumerable fightercraft from both species. GTVA sentries pick up on that battle, but neither the Shivans nor the Guan-di spare any attention from each other, thus the Terrans and Vasudans are able to observe from afar. This revelation sparks GTVA fears of being steamrolled either by the conflict itself or else by its winner; a decision is made to contact both species, in hopes that one will be open to an alliance.
In following the schematics for Aken Bosch's device, the GTVA eventually recreates his communications technology. A dual-pronged mission launches simultaneous negotiations with the Shivans and the Guan-di: its first half backfires, as the xenophobes are again angered at contact by what they deem as inferior beings--the best the GTVA manage is to find out Bosch's fate was indeed terrible. On the other hand, the Guan-di react in a neutral manner, since their extreme focus on the Shivans leaves little room to see the GTVA as either interesting or threatening.
As the war stretches ever-farther into T-V space, the GTVA desperately push to maintain talks with the indifferent Guan-di. Thanks also to several covert GTI ops, gradually the conflict's entire scope is pieced together. The Shivan paranoia and their parasitic grasp on subspace both become evident as the true danger; if they win the war, then all Terrans and Vasudans would be next on their agenda. By contrast, the Guan-di are understood to be fighting a defensive struggle, with no real desire to either control subspace or occupy star systems. A victory for their species would therefore appear likely to cause a unified return to their home territories.
Later on, the GTVA acquires a critical new fact about the Shivans: all their individuals are mind-linked in a rigidly hierarchical collective, with command-and-control originating from a "Shivan Nexus" in their home region of the universe. By the time the Guan-di learned of the Nexus, the Shivans had already massed overwhelming defenses around it, thereby dooming a subsequent Guan-di siege to miserable failure.
After considering the above, the GTVA decides to take a chance that the Guan-di would truly be non-aggressive if the Shivans lost the war. A do-or-die mission is conceived about flying the super-shielded Olympus Mons all the way to the Shivan home region, with an aim to destroy the Nexus and thereby render the entire species helpless. Because the Guan-di are unallied and unsympathetic, the GTVA readies itself to also fight through their fleet when necessary.