Assimilation
Assimilation was the process by which the Borg added new members and new technology to the Collective. 

Borg assimilation was predatory; every species the Borg encountered was assessed to determine whether its biological and/or technological distinctiveness was considered "worthy of being added to the Collective's perfection". If found to be so, the species was set upon and forcibly assimilated; the Collective considered the species' will in the matter "irrelevant". (; , et al.) When a species was assimilated, their neural pathways were restructured to link them to a single collective mind, the hive, and to augment their bodies with cybernetic technology. The end result was them becoming drones. ()

By the 2370s, the Borg had assimilated thousands of species. As of the 24th century, the only species known to have been considered unworthy of assimilation were the Kazon, as the Borg believed that assimilating them would detract from their goal of becoming perfect. ()

Procedure 

The Borg generally did not assimilate individuals, and instead preferred to target larger groups such as the crews of starships and the populations of planets. When in the presence of a small number of individuals, Borg drones would ignore them altogether. This policy would remain in effect until an individual demonstrated some quality found worthy by the Collective, or posed a threat to Borg activities. For example, when the  was first detected by a Borg vessel it was disregarded. By the time the Raven was detected a second time, its crew had developed technologies to elude Borg sensors, making them a more worthy target. ()

The Borg made exceptions and assimilated individuals when circumstances required it, as when they chose Jean-Luc Picard to serve as an intermediary in 2366, or to allow a small party of drones to bolster their ranks. (; )

When engaging a starship, a Borg vessel presumed tactical superiority and locked onto it with a tractor beam. With the target immobilized, the Borg defeated its shields and either extracted sections of the ship with a cutting beam, transported drones to key areas, or both. ()

With the crew of a vessel assimilated or otherwise subdued, the Borg stripped the ship down for parts to incorporate into their own technology. If possible the assimilated ship was towed into a hangar aboard the attacking Borg ship. () It was rare for the Borg to keep an assimilated vessel intact, except in instances where a Borg crew was forced to abandon their own ship and commandeer their victims' ship. (; ; )

Faced with an entire fleet, as in the Battle of Wolf 359, the Borg were willing to destroy individual ships outright, although some might have been spared for assimilation. ()

The Collective typically did not seek out individuals or starships, assimilating them only as encountered. It was only known to actively target worlds and civilizations, ranging from small colonies to the entire realm of fluidic space. (; ) The tactics of these large-scale assimilation missions varied. An entire fleet was dispatched to assimilate Species 10026, but on two occasions, a single ship was assigned to conquer the entire Federation. If the Borg did not choose to hold an assimilated planet, they removed its populace and any artificial structures from the surface. Alternately, they could maintain a presence on the planet, terraforming its environment to meet their needs. (, , )

The Borg had a standard set of hails which were sent to those targeted for assimilation. The actual wording varied, but the hails almost always included the following information:
Self identification ("We are the Borg.")
Intention to assimilate the target ("You will be assimilated", "Existence as you know it is over")
The futility of attempted resistance by the target ("Resistance is futile")

The following were known Borg hails:
"You will be assimilated. Resistance is futile." ()
"I am Locutus of Borg. Resistance is futile. Your life as it has been is over. From this time forward, you will service us." ()
"We are the Borg. Lower your shields and surrender your ships. We will add your biological and technological distinctiveness to our own. Your culture will adapt to service us. Resistance is futile." ()
"We are the Borg. Existence, as you know it, is over. We will add your biological and technological distinctiveness to our own. Resistance is futile." ()
"We are the Borg. Your biological and technological distinctiveness will be added to our own. Resistance is futile." ()
"We are the Borg. You will be assimilated. Resistance is futile." ()

Technique 

Little was known about the Borg assimilation technique prior to 2368. Observations since that time demonstrated that the Borg assimilated an individual by projecting a pair of assimilation tubules into the victim's neck, injecting nanoprobes into the bloodstream that began connecting the new drone to the hive mind. This was accomplished the moment a Borg drone was within arm's reach of the target. (; ; ) Only humanoids have been seen as members of the Borg Collective.

During initial stages of assimilation, Borg nanoprobes began attaching themselves to the victim's red blood cells, allowing them to circulate throughout the body. () Within minutes, the nanoprobes spread visibly through the capillaries of the victim's skin. The victim, at this point, still retained his or her individuality and had virtually none of the Borg's standard array of defenses. Left unchecked, the nanoprobes soon begin self-replicating and producing larger constructs that form the necessary Borg implants. The body was also injected with stabilizing metals such as lithium so the body can handle nanoprobes. Seven of Nine could remember the smell and taste of the metals. () Among the first major structures assembled was the neural transceiver, allowing the Collective to tap into the victim's mind and usurp control of his or her body. A vocal subprocessor was also installed. By this time, the new drone's skin coloration had changed to a pale gray and mottled as some small implants began to emerge inside and outside the body. In some cases, the skin and face became at least slightly deformed due to the implants growing in and on the body. (; ; ) The drone was then taken to a Borg facility to have larger implants surgically installed, including tools, weapons and exoplating. ()

According to Jean-Luc Picard, when it comes to the assimilation of an individual's mind, the process can take hours for a newcomer, as the Borg have to learn the victim's mind. However, if an ex-Borg were to be assimilated again, their mind would be taken in seconds, as the Borg already know the ex-Borg's mind. ()

In a daydream of The Doctor's, the Borg were able to conduct assimilation by penetrating the defenses of a vessel with an "assimilation virus," the effects of which were nearly instantaneous. ()

Treatment and defenses 
Methods for preventing or overcoming Borg assimilation are of paramount importance to cultures that refuse to abandon members of their society captured by the Collective.

In 2153, Phlox determined that exposing himself to omicron particles could disable the nanoprobes injected into his body by drones using technology originating in 2373. This method was uniquely applicable to Phlox due to his Denobulan physiology and his immune system, which made him unusually resistant to assimilation. ()

The most basic, and arguably most practical remedy was to euthanize the intended victim either prior to or in the early minutes of assimilation, before the nanoprobes could install standard Borg defenses. During the Borg's raid of the , Captain Picard saw this approach to be the lesser of two evils, believing his assimilated crewmen were irrecoverable under the circumstances and better off dying as individuals than living as drones. ()

When rescuing Picard himself in 2367, the crew of the  were not under direct attack by the Borg and therefore had the luxury of considering other options. Upon connecting his neural net to Picard's Borg implants, Lt. Commander Data was able to isolate Picard's individual mind from the Collective. Disconnecting Picard from his implants was considered a risky procedure, but upon the destruction of the cube that assimilated him the Collective lost its hold on him. Physical recovery was swift, although the psychological trauma was more severe. () While the implants were removed, sufficient physical alterations lingered such that Picard could still perceive the Collective many years later. ()

In 2368 a Borg cube was disabled in an electrokinetic storm in the Nekrit Expanse, causing approximately 80,000 drones to be disconnected from the hive mind. These former drones settled on a nearby planet, where their limited medical resources allowed them to remove most, but not all, of their cybernetic implants. After the population descended into war, they elected to form a new hive mind as the Cooperative. ()

The crew of the  was forced to sever Seven of Nine's link to the Collective when, through her, the Borg reneged on its alliance with the starship. Using a neural transceiver installed in him by the Borg Cooperative and a Borg alcove installed aboard Voyager by the Collective, Chakotay tapped into Seven's consciousness in order to distract her while B'Elanna Torres shorted out the console she was attempting to assimilate. ()

The Brunali genetically engineered Icheb with a pathogen that would infect the Collective after they sent him to be assimilated. After this pathogen killed all of the adult Borg aboard the cube which assimilated Icheb, the ship's maturation chambers prematurely released the juvenile drones who were not yet fully connected to the Collective, giving Voyager an opportunity to liberate them in 2376. ()

A neural suppressant developed by Voyagers EMH in 2377 made it possible for Kathryn Janeway, Tuvok, and B'Elanna Torres to be physically assimilated without being connected to the hive mind and losing their individuality. This allowed them to surreptitiously operate within a Borg cube and sabotage its central plexus. Following their mission the three officers were returned to Voyager where their implants were safely removed without medical complications. Use of the neural suppressant apparently correlated to the lack of psychological trauma suffered in comparison to Picard's experience. ()

Following Voyagers sabotage of the central plexus, the Borg drones who had been connected to Unimatrix Zero were able to regain their individuality and mount a resistance against the Collective. They were not, at least initially, able to remove their Borg implants due to the urgency of the conflict. ()

Upon arriving in 2378 from an alternate future, Admiral Kathryn Janeway possessed several defenses against the Borg, including a neurolytic pathogen that prevented Borg nanoprobes from linking her to the hive mind while infecting the Collective. ()

Complications 
Successful liberation of an assimilated drone depended largely on the relation between the period of time spent as a drone versus time spent as an individual. Adults and children who were assimilated for only a short time were often easily reintegrated back into their old lives following disconnection from the hive mind. (; ) However, drones who had spent the majority of their lives within the Collective resisted the very notion that they were better off as individuals, and could retain an admiration for aspects of Borg philosophy. Such drones could feel small or lonely without the "voices" of the entire Collective in their thoughts. (; )

In either case, the psychological impact of recovering one's individuality – and thus, the ability to feel the trauma of assimilation and the guilt of one's association with the Borg's atrocities – could be monumental. (; ) Former victims would often feel discomfort within simulations of working Borg vessels or real, disabled ones. (; )

From a medical standpoint, there were many risks in leaving the Borg Collective, primarily when the implants ceased to suppress the immune system and the body's organs began rejecting implants that have been given sole dominion over vital functions. The extraction of these implants could be challenging even for a skilled surgeon. One known type of complication occurred when deactivated microscopic implants become lodged against one of the cranial nerves. () Even after the successful removal of the cybernetics, the liberated drone might not have had access to medical technology that was sufficiently advanced to replace whatever body parts were amputated during assimilation. () Certain implants, such as the cortical node, ocular implant, and assimilation tubules, could not be safely removed by Federation medicine as of 2378. ()

Memorable quotes

Appendices

Related topics 
 Borg species

External link 
 

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