The history of the Borg shows the gradual development of the Borg species.
The origin of the Borg is vague. What is known is by hearsay, brief contacts with Borg survivors, and even the Borg itself.
According to the Borg Queen, the species known as the Borg started out as normal lifeforms without any cybernetic enhancements thousands of centuries ago. Over the years, they evolved into a mixture of organic and artificial life. (Star Trek: First Contact; TNG: "Q Who") The Borg originated in the Delta Quadrant, (Star Trek: First Contact; VOY: "Dark Frontier", "Dragon's Teeth") where they already existed by 1484. At that time, only a handful of star systems had been assimilated by them and they had many encounters with the Vaadwaur. (VOY: "Dragon's Teeth")
By 2373, the Borg had assimilated thousands of star systems. (Star Trek: First Contact; VOY: "Unity", "Scorpion", "Scorpion, Part II") Their territory was intersected by a narrow corridor of space filled with gravimetric distortions, eventually nicknamed the "Northwest Passage" by the crew of the Federation starship USS Voyager during the Borg's conflict with Species 8472. (VOY: "Scorpion") The farthest border of the Borg realm within the Delta Quadrant seemed to be the Nekrit Expanse. (VOY: "Fair Trade", "Unity", "Distant Origin")
The Collective had their own territory and ventured out, beyond it, on exploration missions. (TNG: "Q Who"; VOY: "Dragon's Teeth", "Unity") At one time, Voyager was thrown 9,500 light years, beyond Borg territory and ten years closer to Earth. (VOY: "The Gift") Four years later, the starship still encountered Borg vessels. (VOY: "Collective", "Child's Play", "Unimatrix Zero", "Unimatrix Zero, Part II", "Endgame") Since the Borg had such extensive transwarp networks throughout the Milky Way Galaxy, they could effectively project their presence anywhere in a comparatively short amount of time. (TNG: "Descent", "Descent, Part II"; VOY: "Dark Frontier", "Inside Man", "Endgame") While the Borg did have a large expanse of their own territory, it was finite, and any forays elsewhere were simply invasions of other territories. (TNG: "Q Who", "The Best of Both Worlds"; Star Trek Generations; DS9: "Emissary"; VOY: "Blood Fever", "Hope and Fear", "The Raven")
Within the Delta Quadrant, the Borg had a vast structure called the Unicomplex. This structure was made up of thousands of sub-structures and housed many of their vessels. It was believed the Unicomplex was the Borg headquarters. (VOY: "Dark Frontier")
When the Borg started using transwarp hubs, (VOY: "Endgame") they could appear anywhere in the galaxy, giving them the ability to assimilate species with little or no warning at all and within very short periods of time. Their vessels were equipped with specially designed conduits to withstand the temporal stresses when traveling through transwarp conduits. Borg starships had the ability to travel through time. They once tried to assimilate a species by traveling back in time. (VOY: "Inside Man"; Star Trek: First Contact)
Although the Borg were normally not active in the Alpha Quadrant in 2063, a Borg sphere traveled back in time from 2373 to that year. The craft's occupants had the sole purpose of preventing First Contact between Humans and Vulcans, thereby helping the Borg to assimilate the Human species. They attempted to achieve their outcome by destroying the Phoenix, the spaceship that Zefram Cochrane used to historically perform the first warp-powered flight, subsequently bringing Earth to the attention of a passing Vulcan vessel. (Star Trek: First Contact)
A Federation starship also from 2373, the USS Enterprise-E, thwarted the Borg attempt by destroying the Borg sphere, and a section of its broken hull landed in Earth's North Pole. (Star Trek: First Contact; ENT: "Regeneration") But before the sphere's destruction, some Borg drones (including the Borg Queen) transported aboard the Enterprise and began to assimilate the ship and many crewmembers. They used the Enterprise as their base of operations in an attempt to continue their objective to alter history and also attempted to build an interplexing beacon on the Enterprise deflector dish to contact the Collective of the 21st century. They failed to prevent First Contact and were defeated by Captain Picard and Data. The Queen and all the remaining drones perished aboard the Enterprise; their organic components were dissolved by very corrosive plasma coolant and the Queen's artificial spinal cord was broken to ensure she was dead. (Star Trek: First Contact)
The same year, Zefram Cochrane, during his commencement address at Princeton, revealed his unusual experience. He mentioned cybernetic creatures from the future, whose ultimate goal was to enslave the Human race, who tried to stop his first warp flight, if it weren't for a group of Humans also from the future. No one seriously believed Cochrane, well known for his imaginative stories while intoxicated, and he recanted his claim a few years later; although a record of his speech still remained. (ENT: "Regeneration")
By 2145, and after assimilating thirteen species, they learned of the existence of the Omega molecule which they referred to as Particle 010. The Borg believed the Omega to exist in a flawless state and regarded it with near-reverence and all Borg were ordered to assimilate it at any cost. They managed to synthesize a relatively stable single molecule of Omega, which resulted to the destruction of 29 Borg vessels and 600,000 drones. They designed a harmonic resonance chamber that could theoretically stabilize the molecule, but never had enough Boronite to synthesize more Omega molecules. (VOY: "The Omega Directive")
In 2153, the remains of the Borg sphere that was destroyed in 2063 were discovered in Earth's Arctic Circle. The A-6 excavation team discovered the Arctic debris field where much of the Borg sphere remained, severely damaged and buried under a glacier. After traveling to the wreckage, the team also found two frozen drones in the ice, and allowed them to regenerate. The Borg drones assimilated the entire team of scientists and commandeered their transport Arctic One, continually enhancing its warp drive and installing a weapons system.
Three days later, the Borg left Earth. Although they managed to assimilate several Tarkaleans, who tried to do the same to Denobulan doctor Phlox, the crew of the Starfleet ship Enterprise NX-01, which included Phlox, was successful in preventing the Borg drones, of which there were more due to the original drones' assimilation of the Tarkaleans, from reaching their homeworld and resuming their attempt to enslave Humanity. Enterprise was responsible for the destruction of the assimilated arctic transport and every Borg drone aboard the craft.
However, the ship's captain, Jonathan Archer, having determined that the cybernetic aliens had probably been the same as in Zefram Cochrane's Princeton commencement address, also learned that the Borg had sent a subspace message before their destruction that contained spatial coordinates pinpointing Earth's location. Because Phlox had momentarily been a part of the Borg's hive mind, he had heard the message. However, the signal would take two hundred years to reach its destination, deep in the Delta Quadrant, alerting the Borg there.
In 2293, two starships, the SS Lakul and SS Robert Fox, were carrying El-Aurian refugees to Earth when they became caught in an energy ribbon that caused the destruction of both ships. (Star Trek Generations) However, 47 El-Aurians from the Lakul – including Guinan, who later served as Ten Forward's bartender aboard the USS Enterprise-D – were saved when they were beamed aboard the USS Enterprise-B by Montgomery Scott and took with them the story of their species' dealings with the Borg. (Star Trek Generations; TNG: "The Child", "Q Who")
Starfleet had no record of the name "Borg" and no connection was made between all these events, the cybernetic beings found 140 years before, and those who had attacked the El-Aurians. Therefore, it was not until the time the Lakul survivors were retrieved that Starfleet first became officially aware of the Borg and opened a file on them on stardate 9521.6. (ENT: "Regeneration"; VOY: "Scorpion")
During the years 2354 through 2356, the Borg were studied by Human exobiologists Magnus Hansen and his wife Erin. Together with their daughter Annika, they ventured out in the USS Raven to seek the Borg.
On stardate 32623.5, a Borg cube exiting a transwarp conduit encountered the Raven, which at this point had changed its course without informing Starfleet. The Raven was beyond the Romulan Neutral Zone and disobeyed a direct order to return. At 2,000 kilometers, the cube scanned the Raven and found it no threat, unwittingly proving Magnus' theory that the Borg would not attack as long they were no threat or a target for assimilation. The Borg vessel turned away and was followed by the Raven at a distance of five million kilometers, matching the cube's heading and speed.
After three months, on stardate 32629.4, the Borg cube opened a transwarp conduit and traveled to the Delta Quadrant, the Raven following in its wake. Unknown to the Borg, the Hansens developed new technologies to keep hidden from Borg sensors, such as multi-adaptive shielding to hide the Raven and a personal bio-dampener so someone could visit a Borg vessel without being detected. Without the Borg's knowledge, the Raven was now very close to the cube while Magnus Hansen studied them. He witnessed how two drones from another sub-unit de-activated a drone who was damaged beyond repair when a plasma conduit exploded, removing its usable components.
Some time later, the Borg cube linked with another vessel and received over fifty thousand new drones. The Hansens stealthily beamed over newly arrived drones to identify them. A tactical drone, a former Ktarian male, was beamed over to the Raven while he was regenerating in his alcove. Because its previous designation was Three of Five Tertiary Adjunct of Unimatrix One, this drone was tagged with a subdermal probe so he could be traced by the Hansens. Magnus believed this drone worked for the Borg Queen and searched its cranial transceiver logs for evidence.
In 2356, the Borg detected the Raven and perceived her as a threat when it was visible on their sensors for 13.2 seconds. This occurred because the Raven was hit by a subspace particle storm which knocked out their multi-adaptive shields. The Borg cube required three hours to track down the Raven because Magnus masked their warp trail. The cube exited a transwarp conduit only 3.2 light years from the Raven and intercepted it in less than an hour.
The Borg assimilated the Hansens. From then on, Annika Hansen was known as Seven of Nine, and was a Borg drone until she was rescued in 2374 by USS Voyager. In 2375, father and daughter met once again, although Magnus was still a drone serving in Unimatrix 01. It is unknown what happened to the drone formerly known as Erin Hansen. The USS Raven was partially assimilated and crashed on a remote moon in B'omar space. (VOY: "Dark Frontier", "The Raven")
In 2364, the Borg were believed to be responsible for the destruction of several Romulan and Federation outposts along the Romulan Neutral Zone in sectors 30 and 31. This became evident when the Enterprise-D encountered a similar outpost with an almost identical signature a year later. (TNG: "The Neutral Zone")
In 2365, a Borg cube traveling near System J-25, seven thousand light years away from Federation space, detected a starship. The sixth planet in that system, a Class-M, seemed to have the same characteristics as some Federation and Romulan outposts near the Neutral Zone. Their cities were removed from the planet's surface. When the Borg cube arrived, it scanned the unknown vessel.
The strange vessel hailed the Borg, but they did not respond to it. They were slow. Instead, they transported a drone to the engineering section of the unknown starship, right through the vessel's shields. The drone paid no attention to the lifeforms present and walked towards a com panel. Before he could reach it, a phaser shot knocked him down. Moments later another drone was sent and after he materialized, continued towards the panel. Again he was fired upon but this time his personal shield stopped the shot. The Borg had adapted. After the drone extracted information from the com panel, it reached over to the fallen drone and removed some components, after which both drones dematerialized.
After the Borg analyzed the information, they knew with whom they were dealing, the Federation starship USS Enterprise-D under the command of Captain Jean-Luc Picard. They also concluded that the Enterprise-D was unable to withstand them, since her defensive capabilities were insufficient. The Borg hailed the Enterprise and told them to not defend themselves as they would be punished for it, interrupting Picard's greeting, and they locked a tractor beam onto the ship. The beam held the starship in place and drained their defensive shields.
The Borg cube was fired upon by the Enterprise when it tried to escape, but to no avail. After eighteen seconds, their shields were gone and the Borg used a cutting beam to remove a part of the ship, saucer sections 27, 28, and 29 on decks 4, 5, and 6. Again the cube was fired upon by the Enterprise. This time, the Borg released the tractor beam; they had sustained twenty percent damage.
An away team from the Enterprise boarded their vessel and watched how a drone performed some tasks. As the away team scouted the ship, they found a Borg maturation chamber and also noticed that the Borg vessel was repairing itself. Immediately, the away team was beamed back to the Enterprise.
When the Borg discovered the Enterprise running, they started to pursue it. Although the Enterprise was reaching warp 9, the Borg cube could easily match their speed and even gained on them. Photon torpedoes fired on them by the Enterprise detonated without causing any damage to the cube.
The Borg fired weapons at the Enterprise designed to drain their shields and was still closing in, even though the Enterprise seemed to have reached her maximum speed. After a second shot, the Enterprise again fired photon torpedoes at the Borg, but without any effect. After the Borg fired their third shot, the shields of the Enterprise were gone and they were able to knock the ship out of warp. After the Enterprise lost warp speed, the Borg immediately re-established their tractor beam, but without any warning the Enterprise broke free and sped away from the Borg.
In 2366, the Borg sent a cube to the Alpha Quadrant on a mission to assimilate Earth.
Within the Alpha Quadrant, the Borg first assimilated the nine hundred inhabitants of the Federation colony New Providence. Analysis of the soil revealed the same magnetic-resonance signature the Borg left on the hull of the Enterprise-D the year before. This proved the Borg were not only responsible for the destruction of the New Providence colony, but also the Federation and Romulan outposts in 2364.
The Borg cube continued its journey and encountered the USS Lalo while on a freight run to Sentinel Minor IV. Although the Lalo managed to send a distress call to starbase 157, they were assimilated as well.
Two hours later the Borg cube noticed the USS Enterprise-D and altered its course to intercept, with a speed of warp 9.3. When it reached the Starfleet vessel, the cube dropped out of warp and hailed Captain Jean-Luc Picard personally. The Borg informed him to lower the shields and to transport to the Borg vessel. If Picard failed to comply, the Enterprise would be destroyed. After Picard accused the Borg of aggression against the Federation, the Borg told him that the Enterprise was no match for the Borg cube.
The Borg tried to lock a tractor beam on the Enterprise but failed. Within a few moments the Borg adapted to the modulating shields of the Enterprise and locked the tractor beam, draining the ship's shields. Although the Enterprise fired torpedoes and its phaser banks against them, the tractor beam remained in place. Then the Borg began to cut into the Enterprise hull, causing a decompression in engineering, but the Enterprise managed to break free when Lt. Commander Data, as suggested by Cmdr. Shelby, fluctuated the phaser resonance frequencies while firing upon the Borg vessel. The Borg cube immediately started pursuing the fleeing Enterprise.
When the Enterprise hid within the Paulson Nebula, the Borg had trouble locating them and decided to wait. To force the Enterprise out of the nebula, the Borg launched magnetometric guided charges into it. The cube again locked its tractor beam onto the Enterprise as it tried to flee the nebula. A drone was beamed to the Enterprise bridge and tried to reach Picard, but was shot down by Chief of Security Worf. Two more drones were sent, and one of them captured Picard as the other one threw the charging First Officer Riker against a bulkhead. After this skirmish, the drones transported back to the cube with Picard.
Then the Borg cube disengaged its tractor beam and left the Enterprise behind, resuming its course for sector 001.
In the Borg cube, Picard was told that he would serve to introduce the Borg into Federation culture. Despite his arguments, Picard was told that strength, self-determination, even death, were irrelevant. Resistance was futile; Picard was chosen to speak for the Borg. Some time later, the Borg detected an away team inside the Borg cube. They were trying to locate Picard and to sabotage the cube, but the Borg sent drones after them. While drones were pursuing the away team, they ran into their captain, who had been assimilated, and were forced to flee. The Borg cube was forced out of warp by the away team's sabotage, but the Borg restored their warp capability within a short period of time.
Then the Enterprise was hailed by the Borg. Their former captain introduced himself as Locutus of Borg and told them to surrender. Although the Enterprise's navigational deflector was used as a weapon and fired at the cube, there was no effect and Riker was told by Locutus that his resistance was hopeless. The knowledge Picard possessed was part of the Borg Collective. After this, the Borg resumed their course towards Earth.
The Borg cube was met and engaged by Starfleet at Wolf 359 by forty starships. The Battle of Wolf 359 was a disaster for the Federation; all but one ship was destroyed with the loss of eleven thousand lives, and the Borg vessel immediately returned to its previous heading towards Earth.
While en route, the Borg were contacted by Riker, now captain of the Enterprise-D, who offered to end the hostilities and to prepare for assimilation. Despite that the Borg had Picard, they had not foreseen that this was a ruse and that Picard's knowledge had been used against them. When the Enterprise engaged the cube the Borg did not notice the shuttle which was closing in on them. When the Borg noticed that Worf and Data transported to the cube, they were too late to prevent the kidnapping of Locutus. Although the Borg lost Locutus, they again resumed their course for Earth.
Locutus was brought to the Enterprise, where Data investigated how he was connected to the Borg. There, Data found an opportunity to stop the Borg.
The Borg cube was stopped when it was ordered to enter its regeneration cycle. This was done by Data, who connected himself to Locutus and ordered the regeneration command, effectively putting all the drones to sleep. The command also started a self-destruct mechanism which destroyed the cube.
The Borg not only lost their vessel, but also Locutus when his link with the hive mind was severed when the cube exploded. (TNG: "The Best of Both Worlds", "The Best of Both Worlds, Part II"; DS9: "Emissary")
Picard knew the Borg would investigate the crash and wanted to take advantage of the situation by implanting a hostile program into the drone. When it was re-integrated within the Borg Collective, the program would destroy the Borg from the inside, like a virus. However, this plan was abandoned under pressure of Doctor Beverly Crusher and Geordi La Forge, who had doubts. Instead, the drone was allowed to grow as an individual, since it no longer was a part of the Borg Collective. It even had a name, Hugh.
Eventually Hugh was returned to the crash site with his individuality intact. After he was rescued by a Borg vessel, the former drone was re-integrated within the Collective, but the Borg could not cope with his individuality. As a result, the Borg vessel fell into a state of disarray, and drifted through space until it was found by Lore, Data's brother. (TNG: "I Borg", "Descent")
Later that year, in the Delta Quadrant, a Borg vessel crashed and its survivors, the drones with the designations Two of Nine, Three of Nine, Four of Nine, and Seven of Nine regained their individuality. Because Seven of Nine had been assimilated at a very young age, she could not cope with her individuality. So, she decided to create a small collective between the four of them when the other drones refused to await their rescue and to rejoin the Collective. This action created a collective within a collective.
After the Battle of Wolf 359, the Borg had sent in more expeditions to Federation space. By 2369, these expeditions had resulted in the deaths of tens of thousands of Federation citizens. (TNG: "I Borg", "Descent", "Descent, Part II")
A group of Borg had been disconnected from the Collective after integrating Hugh's sense of individuality into the hive. These were discovered by the Soong-type android Lore and styled himself their leader, gave them individual names, and began cruel experiments on them, attempting to replace their organic brains with positronic components. These Borg became more violent – murdering their victims instead of assimilating them - and directed his followers to launch attacks on targets in Federation space. The Enterprise was lured to them and Lore managed to kidnap Data and manipulate him. The captured crew of the Enterprise helped the rogue Borg group to overthrow Lore. (TNG: "Descent", "Descent, Part II")
In 2371, the Borg assimilated Species 6339, a humanoid warp-capable species located in the Delta Quadrant, grid 124, octant 22 theta. Eleven billion individuals were assimilated, and only a handful managed to escape. (VOY: "Infinite Regress")
In 2373 on stardate 50614.2 a Borg cube in the Delta Quadrant traveling through the Nekrit Expanse was hit by an electrokinetic storm, killing most drones on board. The survivors lost their connection with the hive mind, which caused the reappearance of their own identity, and transported themselves to a nearby class-M planet. Because they had found their individuality again, they also regained the hatred towards other species they had before they were assimilated into the Borg Collective.
This resulted in fights between the different species. There was one group who tried to live in coexistence; they called themselves the Cooperative. However, they were continuously attacked by other former Borg drones, and to stop this they had send out a Federation distress call in the hope someone would answer. The call was answered by a shuttle commanded by Commander Chakotay of the starship Voyager.
Chakotay was injured and Ensign Kaplan was killed after they landed the shuttle. Chakotay was cared for by Riley Frazier, a former drone and Starfleet officer, who used the Borg link to heal Chakotay's wounds. The Cooperative forced Chakotay to re-establish the neural link, via their residual link by which the Cooperative healed him, by starting the neuro electric generator on board the heavily damaged Borg cube for a few minutes. (VOY: "Unity")
On stardate 50893.5 a single Borg cube was sent to assimilate Earth. This was the Borg's second attempt, and on board was a Borg Queen. During this attempt the Borg tried to alter Earth's past by traveling to the year 2063 and preventing First Contact with the Vulcans. The skirmish that followed with Starfleet became known as the Battle of Sector 001.
Although the cube was destroyed by Starfleet, a Borg sphere contained within reached Earth and successfully traveled to 2063. Following the destruction of the sphere by the Enterprise, a contingent of drones (including the Queen) attempted to hijack the Enterprise and began assimilating the ship and crew, but their attempts were thwarted. (Star Trek: First Contact)
On stardate 50984.3 the Borg faced their destruction after they invaded Species 8472's fluidic space with intent to assimilate this species. Unfortunately – for the Borg – Species 8472 DNA encoding was so dense that nanoprobes could not assimilate their cells. Species 8472 responded with an all out attack on the Borg. They used the "Northwest Passage" in Borg space as their entry point, via a quantum singularity, and destroyed any Borg vessel they could find.
The Borg had lost millions of drones and thousand of worlds when, after assimilating a Starfleet probe in the Delta Quadrant, fifteen of their vessels encountered USS Voyager. One of the Borg cubes scanned Voyager with a polaron beam and when finished joined the other vessels en route to Species 8472.
In the following battle all fifteen Borg ships were destroyed. Unknown to the Borg at the time, Voyager had found those ships and one of the vessels who destroyed them, a Species 8472 bio-ship. On one Borg cube, Species 8472 had stacked Borg remains on each other, as if to scare them off. As far as Species 8472 was concerned, "the weak will perish".
In five months the Borg were attacked more than a dozen times and lost every single time.
A few days later a Borg cube encountered USS Voyager and locked a tractor beam on her and informed the crew that they would be assimilated. Instead, the Borg were offered an alliance. The Borg Collective learned that Voyager had found a way to attack Species 8472 on a microscopic level. The Doctor had discovered a way when he was treating Harry Kim, who was infected by Species 8472 cells. In turn for free passage of Voyager through their space, the Borg would gain their knowledge.
Although at first the Borg would not negotiate with Voyager they became interested when they received a sample of Voyager's technique to attack Species 8472. They beamed Captain Janeway on board their vessel and asked her what she wanted. At first the Borg refused Janeway's plan to give them the technology after Voyager cleared Borg space and made clear that it was essential for their and her survival. When Janeway told them there was no alternative other than her proposal, the Collective agreed. If the Borg did try to assimilate Voyager, The Doctor would destroy the data on how to attack Species 8472. The Borg would need to work together to develop a weapon while escorting Voyager through their space.
At this time the cube came under attack from Species 8472, who were attacking the nearby planet. The cube managed to escape and took Voyager with it, still attached to the cube via a tractor beam. The Borg/Species 8472 conflict extended to the year 2374.
Two Borg drones escorted Janeway and Tuvok. Janeway asked them to join her at grid 92 of sub-junction 12, near the center of the Borg cube, where they would work on the weapon. For efficiency, the Borg wanted to link Janeway and Tuvok with the Borg Collective, as they found verbal communication primitive and inefficient, via a neural transceiver. Although Janeway told them that they worked better via verbal communication and as individuals, not linked into the Hive mind, the Borg were not interested. Only when Janeway suggested that they choose a single Borg to speak for them like Locutus, and threatened them that the deal would be void otherwise, did the Borg listen. The Borg choose Seven of Nine to speak for them.
The Borg concurred with Janeway's suggestion for a large scale weapon but dismissed using photon torpedoes. Instead the Borg devised a multi-kinetic neutronic mine, a weapon of mass destruction. The Borg heard Janeway's objections, that it would take too long to fabricate the necessary nanoprobes and by that time the Borg would have lost the war, among other things. The Borg agreed based on their present situation.
While studying Voyager's data on the bio-ship, the Borg ship was hailed by Commander Chakotay and they were informed that Species 8472 seemed to be in telepathic contact with Kes. Which might suggest that they already would know about the plans to attack them. Upon hearing this the Borg altered course. Although this would postpone an attack the Borg asked Janeway for the modified nanoprobes so they could start constructing a prototype weapon. Janeway refused, she first wanted to have left Borg space, and did not budge even when the Borg threatened to send five hundred drones to Voyager. Voyager's crew would fight to the death if this would happen and the Borg would lose the nanoprobes.
The Borg dropped their demand and told Janeway and Tuvok to develop a launching system. Moments later Voyager and the Borg cube were attacked by a single bio-ship. To prevent the destruction of Voyager and their nanoprobes the Borg cube positioned itself between Voyager and the bio-ship. After the first hit the cube crashed deliberately into the bio-ship, destroying both of them. Before their destruction the Borg Collective beamed Seven of Nine, together with some drones, Borg alcoves, Janeway and Tuvok to one of Voyager's cargo bays.
The Borg explained, by means of Seven of Nine, that they destroyed their vessel to protect Voyager. Because of this the Borg wanted to modify their agreement with Voyager and demanded to be brought to the nearest Borg cube some forty light years away. Unknown to the Borg Commander Chakotay, who was now in command because Captain Janeway was severely wounded when the cube was hit, was altering their agreement.
The drone Seven of Nine was brought to the captain's ready room. Here the Borg learned that the agreement was changed and they would be transferred to a planet or moon with the modified nanoprobes. When the Borg optioned to assimilate Voyager, Commander Chakotay told them if a single drone would leave the cargo bay he would decompress that entire deck. A drone floating in space would not pose a threat. The Borg told him that Humans were erratic, disorganized, every individual entitled to their own small opinion, every decision debated. They lacked harmony, cohesion, greatness. This would be their undoing. The Borg suspected something like this might happen before they entered Janeway's agreement.
Back in the cargo bay Seven of Nine was ordered to take control of Voyager and to enter the realm of Species 8472 when Matrix 010, Grid 19 was attacked by bio-ships. Eight planets were destroyed, 312 Borg vessels disabled and 4,000,621 drones were killed. The Borg took control of the navigational deflector and created a singularity which pulled Voyager into the realm of Species 8472. Although the cargo bay was decompressed by Chakotay the drone Seven of Nine survived. She informed Chakotay of their situation and to prepare for combat with bio-ships. At that time Chakotay realized that the Borg started the war and not Species 8472. In their search for perfection the Borg made a grave tactical error.
When Seven of Nine met Captain Janeway, The Doctor had healed her wounds, on the bridge. She was told Voyager would fight Species 8472 on their own territory. She would work together with Tuvok on the modified nanoprobes and to adapt Voyager's weapons and defensive systems. Voyager was attacked by four bio-ships and fired their nanoprobe enhanced photon torpedoes, destroying all four ships. Afterward Seven of Nine brought Voyager back into the Delta Quadrant where they again were attacked by bio-ships. When Voyager's high yield warhead exploded thirteen bio-ships were destroyed and the other ships fled. This forced all remaining bio-ships in the Delta Quadrant to return to fluidic space.
After Seven of Nine regained full contact with the Borg Collective they broke their alliance with Voyager. The Borg had prevailed and Voyager and its crew would be assimilated. Seven of Nine took over helm control via her assimilation tubules. Unknown to the Borg Commander Chakotay made a link with Seven of Nine via a neural transceiver to distract her, via images of her past and reminding her of her humanity. This gave Chief Engineer B'Elanna Torres the opportunity to create a power surge which knocked the drone unconscious and permanently severed her link with the hive mind.
23 outposts were assimilated in a matter of hours after which hundreds of Borg vessels attacked and assimilated the Species 116 homeworld. About ten or twenty thousand were able to escape. Arturis was one of them. He blamed Captain Janeway for the assimilation of his world because the alliance between Voyager and the Borg prevented the Borg's destruction, and he tried to get Voyager assimilated. (VOY: "Hope and Fear")
In 2375, the Borg were contacted by a 29th century Borg drone. The existence of this drone was the result of a transporter accident where Seven of Nine's nanoprobes interacted with the mobile emitter of The Doctor. Afterward, Ensign Mulcahey's DNA was used to create its Human form. It would be the first time a Borg drone was reproduced instead of assimilated. The drone's designation was One, and its curiosity caused it to seek contact with the Borg Collective.
The Borg detected a proximity signal in Unimatrix 325, Grid 006 (somewhere in the Delta Quadrant) and a Borg sphere altered its course accordingly. Via a transwarp conduit, it could reach the coordinates within approximately three hours.
The Borg made contact with Voyager. After a scan they used a tractor beam to hold Voyager and hailed them, informing them of their oncoming assimilation. Suddenly the tractor beam disengaged because Voyager's shields were re-modulated. A moment later they were fired upon but the Borg were able to invert Voyager's phaser beam with a feedback pulse, taking out their warp drive.
One transported himself into the Sphere and told the Collective to stop the attack on Voyager. The Borg told him he would be assimilated and that resistance was futile. When One tried to reach a Borg alcove, drones tried to stop him, but they failed. The Sphere's navigational controls were taken over by One and he directed the vessel to a nearby proto-nebula. Although the Collective warned One to stop and terminate his interface with the Borg Collective, he steered the Sphere into the nebula, causing the Borg vessel to implode.
On stardate 52356.2 a Borg cube was destroyed in the Delta Quadrant. Its debris field was about 120 kilometers wide. This happened after they assimilated a Species 6339 vessel. The vinculum of the cube was infected by a synthetic pathogenic virus which was carried by members of this species. Unknown to the Borg, this virus was specifically designed to attack them.
Although normally the Borg would investigate a destroyed Borg vessel, it is unknown if they did so with this one. Future events suggest Species 6339 were not successful in re-introducing the virus into the Borg Collective. (VOY: "Infinite Regress") Between stardates 52542.3 and 52619.2 a Borg probe in the Delta Quadrant detected the Intrepid-class Voyager in Unimatrix 424, Grid 116. The Borg informed them of their imminent assimilation and although Voyager could match their firepower, the Borg attacked. During this skirmish the Borg's primary shield matrix went off line and a photon torpedo was beamed on board. Although a drone tried to disarm it, the torpedo detonated. Because the detonation took place near their power matrix, it caused a chain reaction which destroyed the entire ship, killing everyone on board. Unknown to the Borg, Voyager salvaged eight kilotons of debris in search for components they could use. Although Voyager's crew found a transwarp coil, it was of no use to them because it was damaged beyond repair. They did find data nodes, one of them containing tactical data and Borg ship movements. At this point, they devised a plan to steal a transwarp coil from the Borg.
Eight light years away, a heavily-damaged Borg scout ship, traveling at warp 2, was regenerating after it was hit by an ion storm. This had damaged a great deal of the ship and shields, weapons systems and transwarp drive were off line. Three days later the Borg vessel was joined by Voyager, who had masked their warp signature to prevent detection by the Borg.
Although Voyager tried to hide, they were detected. The Borg contacted Seven of Nine via her neural transceiver and she was told the Borg knew about Voyager's plans to infiltrate the Borg sphere. They threatened to destroy Voyager if Seven did not return to the Borg Collective. The Borg found Seven unique and wanted her back.
At 0600 hours, the sphere detected a vessel, a Federation shuttle, and tractored it into a docking port along the central radius for assimilation. When they dropped their shields an away team from Voyager beamed over to the Borg sphere. Unknown to the away team Seven of Nine was contacted while they were en route to the transwarp coil.
An explosion in one of the corridors brought the sphere defensive shield down and one of their transwarp coils was transported to Voyager. While the away team fled to their assembly point Seven of Nine remained behind. At the same time the sphere charged its weapons and altered course for Voyager. Although Janeway tried to convince Seven to go back she had no choice other to leave her when a force field was erected between them.
When the away team left, the Borg sphere opened a transwarp conduit and traveled to the Unicomplex. There, Seven of Nine, escorted by two drones, was welcomed home by the Borg Queen.
The Queen explained to Seven that her escape from the Collective was not really an escape but that she was allowed to leave. In fact she was the only drone ever to leave the Collective. Her experiences on Voyager would add to the Borg perfection and she was told to regenerate in an alcove, to order her thoughts. When Seven's regeneration cycle ended the Borg had enhanced her visual cortex and added a neural processor adjunct, designed to increase her synaptic efficiency. Her memory was also assimilated by the Borg. The Borg did not want another drone, but instead wanted the individual Seven of Nine for the sole purpose of assimilating Humanity. The Borg failed the first time and with the help of Seven of Nine's Human perspective they hoped to assimilate the Humans definitively.
The Borg forced Seven of Nine to help assimilate Species 10026, all 392,000 of them, just to remind her what it was to be Borg. Upon arrival at their homeworld the Borg were attacked by them. Although the Borg had already assessed the strength and weaknesses of species 10026 the Borg Queen was willing to destroy the ship they were on simply to coerce Seven to come up with a solution. After the shield geometry was altered their ships were no longer a threat to the Borg. Because of Seven's hesitation to monitor the assimilation process in the primary assimilation chamber she was assigned to help with repairs on the shield matrix.
While en route, Seven was injured, but two Borg drones healed her wounds. She even stopped someone who tried to avoid assimilation. Afterward she managed to beam several members of species 10026 to a damaged vessel. Seven was told by the Queen that species 10026 was already enhancing the Borg perfection but she detected the refugees Seven beamed onto the ship. The Queen used this moment to force Seven to abandon her Human sentiments, such as compassion and guilt, about the destruction of a species. To make clear that they were one. To Seven's surprise the Queen let the vessel go. When Seven asked her if she thought compassion was irrelevant the Queen did not answer.
Unknown to the Borg, Voyager had devised a plan to rescue Seven of Nine.
Seven of Nine was given the task to program nanoprobes for a new mode of assimilation, via a biogenic weapon detonated in a planet's atmosphere, which would release nanoprobe viruses causing a gradual assimilation of the target species. This weapon was meant for highly-resistant species. Because the species in question was Species 5618, humanity, Seven refused to cooperate. Even a threat to turn her into a drone could not persuade her. When Seven accused the Borg of murdering her family the Queen denied, stating they were given perfection. She then made a drone step forward, Seven of Nine's father, Magnus Hansen.
At that time Seven's interplexing beacon received a message from Captain Janeway telling her that they were on the way to rescue her. Because Seven was linked to the Borg Collective the Queen also knew they were coming.
The Borg found Janeway's shuttle within a few moments. They used technology the Hansens developed and the Borg assimilated: multi-adaptive shielding. Although the Borg had detected the vessel, with three lifeforms and a hologram on board, the Borg Queen tried to persuade Seven to rescue them. Unknown to the Borg, Tuvok and Captain Janeway had entered the unicomplex and were on their way to the Queen's chambers. When the Borg finally tracked the Federation shuttle and locked a tractor beam on it Seven tried to attack the Borg Queen but was stopped by her. At that moment Captain Janeway walked in and threatened to destroy the Queens chambers if she did not let Seven of Nine go, willing to die herself. After the Queen ordered drones to assimilate them Seven told Janeway to destroy the power node above the Queen's alcove. This would disrupt her command interface. After this the shuttle Delta Flyer was able to beam them out of the unicomplex.
Several Borg cubes pursued the fleeing shuttle. When it opened a transwarp conduit a Borg Queen's vessel followed them in. The Borg vessel gained on them while it fired at their engines. When the shuttle entered normal space Chakotay ordered a full spread of photon torpedoes to collapse the transwarp exit aperture. The Borg Queen's vessel was destroyed by the collapse of the aperture.
Voyager managed to get twenty thousand light years, a good fifteen years closer to the Alpha Quadrant, out of the Borg transwarp coil before it failed, as was noted in the captain's log on stardate 52619.2. (VOY: "Dark Frontier")
By 2376, after Seven of Nine had been rescued from the Borg Collective, the other drones escaped from the Borg and had their implants removed on Inavar Prime. The drones went in search for Seven of Nine to break the link which held their Collective intact. Although the link was finally severed, they only had a month to live due to the extensive integration of the link. (VOY: "Survival Instinct")
In that year a Borg sphere detected a 9.8 warp signature strong enough to penetrate subspace. The location of this signature was the Brunali homeworld, less than a light year from a transwarp aperture. When the sphere exited the aperture it detected a Brunali transport vessel and the USS Voyager.
The Borg locked a tractor beam on both ships and informed the occupants of their upcoming fate: being assimilated by the Borg. Although Voyager fired her phasers the Borg vessel kept both ships locked.
When the Brunali transport vessel was tractored inside the Borg sphere it exploded, causing severe damage to the sphere. This gave Voyager the opportunity to escape. Unknown to the Borg, Voyager had beamed a photon torpedo on board the vessel set to detonate when it was inside the Borg sphere. (VOY: "Child's Play")
Unimatrix Zero was a virtual construct made by Borg drones with a genetic mutation. The Borg perceived this mutation as an illness and wanted to eradicate it. To protect themselves the Unimatrix Borg devised a nanovirus which would make them undetectable by the Borg Collective but they were unable to introduce the virus into the Collective. So they contacted the former drone Seven of Nine for help. Together with the crew of USS Voyager the nanovirus was improved so they would be aware of Unimatrix Zero after leaving it.
In an effort to destroy it the Borg Queen sent drones into Unimatrix Zero, and even visited it herself. When she became aware of Captain Janeway's plans she tried to tempt her by sending Voyager directly to Earth, as long as she would not interfere between the Borg and Unimatrix Zero. Janeway refused.
The central plexus of a Borg cube was infiltrated by a Voyager away team, whose members were assimilated by the Borg but retained their individuality because The Doctor had prevented the link with the hive mind. After they released the nanovirus the Borg started to lose contact with drones. The Borg captured Captain Janeway, now a Borg drone, and she was interrogated by the Borg Queen to give her an antidote. The Queen even destroyed some cubes on which she could no longer hear a few drones to persuade her.
Although the Borg could not stop the nanovirus they managed to alter it. The virus would also stop a drone's autonomic functions, making it die within minutes. The Borg Queen gave Janeway an option: make the drones return to the Collective or let them die. Although Janeway ordered her first officer that Unimatrix Zero could no longer exist the Queen was fooled. It was an order to destroy Unimatrix Zero.
The Borg already lost control over a Borg sphere which was now under the command of Korok, a Klingon Borg drone and former occupant of Unimatrix Zero. Together with Voyager the Sphere destroyed Unimatrix Zero by interrupting the interlink frequency via their modified deflectors.
This action caused the Borg to lose control over several vessels in the Delta and Beta Quadrants. One of those ships was a Borg scout vessel at the edge of the Beta Quadrant. The Unimatrix Zero drones would make up a resistance movement under the same name. (VOY: "Unimatrix Zero", "Unimatrix Zero, Part II")
In 2378, a Borg cube almost collided with the Voyager when it left a nebula, located in Spatial Grid 986, within the Delta Quadrant. Although the Borg noticed the Federation vessel, they did not pursue it. Voyager immediately left the nebula upon this encounter.
Some time later, the Borg Queen monitored a viewscreen conversation between Captain Janeway and an Admiral Janeway, who had entered the Delta Quadrant via a temporal rift. She had traveled back in time to bring the crew of Voyager home.
The Borg Queen contacted Seven of Nine when she entered her alcove to regenerate and mentioned the visitor from the future, Admiral Janeway. She knew Voyager was about to return to the nebula and wanted to know why. The Queen warned Seven that if Voyager would enter the nebula they would be assimilated.
Despite this warning the Borg found Voyager entering the nebula again and they sent three Borg cubes to intercept. Although the Borg fired their weapons, and even tried locking their tractor beam, Voyager kept moving on, unhindered. It seemed they were protected by some sort of new armor. While the Borg tried to adapt, the lead cube was fired upon by Voyager with two transphasic torpedoes. The cube exploded almost immediately. The Borg called off the attack on Voyager when the second cube was destroyed. When Voyager reached the center of the nebula they discovered a transwarp hub. At this point the Borg noticed that Voyager turned around and left the nebula. Unknown to the Borg, Voyager's crew was planning to use and destroy the transwarp hub.
Several cubes scanned Admiral Janeway's shuttle when she entered the nebula and used the transwarp hub, but the Borg did not intervene. In the Unicomplex, the Borg Queen was visited by the future Admiral Janeway, who was connected to the hive mind via a synaptic interface. The Queen was told by Admiral Janeway that Captain Janeway was determined to destroy the transwarp hub. Admiral Janeway was willing to help the Borg if a cube would tractor Voyager and transport it back to the Alpha Quadrant. The Borg Queen appreciated that Admiral Janeway wanted to protect the Voyager collective but she wanted her shuttle and its database in return. The admiral's former offer, how to adapt to their torpedoes, was found insufficient. The Queen didn't trust Admiral Janeway because she had already lied to Captain Janeway. Meanwhile, the Borg had found Janeway's position and beamed her into the Queen's chambers.
The Borg Queen congratulated her with hiding right on the Borg's doorstep. When she asked Janeway if she planned to attack the Borg from inside the Unicomplex Janeway didn't answer. A few seconds later the Borg Queen assimilated Admiral Janeway.
The Borg detected that Voyager had entered aperture 823, transwarp corridor 09 of the transwarp hub. When vessels were redirected to intercept, the Borg Queen shook and parts of her chamber started to explode. It turned out the Borg were infected with a neurolytic pathogen, which was carried by Admiral Janeway and designed to disrupt the Hive mind, to bring chaos to order. This infection also caused the destabilization of the force fields surrounding the transwarp conduits, making it possible for Voyager to destroy the transwarp hub.
While the Queen detached an arm from her body, the pathogen started to affect her, she managed to send a Borg sphere after Voyager. After this, the Queen lost a leg and fell to the floor. She told the partially assimilated Admiral Janeway that Captain Janeway would die, that way the admiral's actions would not happen as she would not exist at all. After this her cybernetic parts detached from her organic part and the Queen died, causing a cascade effect throughout the Unicomplex which started to explode.
The Sphere sent after Voyager managed to attack the ship. Moments before Voyager's shields and armor went down, she turned around and entered the sphere itself. When the Borg sphere left the transwarp conduit in the Alpha Quadrant, it was met by a fleet of Starfleet ships. Although it was fired upon, it was not damaged, but suddenly exploded. Voyager emerged from its wreckage. After Captain Janeway made her excuse about their surprise entry, they were welcomed home by Admiral Paris. (VOY: "Endgame")