The SPARTAN Programs are a series of UNSC projects designed to create physically, genetically, technologically, and mentally superior supersoldiers as a special fighting force within the UNSC military. Although the word "SPARTAN" is written in all capitals in reference to the programs in a formal context, the supersoldiers are more commonly known simply as Spartans.
The first effort at creating augmented supersoldiers was the ORION Project, later retroactively dubbed as SPARTAN-I, which used operatives drafted from the UNSC Defense Force. The subsequent programs, SPARTAN-II and SPARTAN-III, were highly successful, but also controversial because of their dubious ethics of using children as candidates. The latest installment, SPARTAN-IV, returned to the program's roots by using consenting adult volunteers from the various special forces units of the UNSCDF. While formerly serving within the various conventional military branches of the UNSCDF, the Spartans were brought under a single organization with the formation of the UNSC military branch known as Spartan to accommodate the growing number of Spartans in the fourth-generation program following the end of the Human-Covenant War.
The Spartan supersoldiers have traditionally been supplied with state-of-the-art equipment and technology, the most recognizable being the iconic MJOLNIR Powered Assault Armor first worn by the SPARTAN-IIs and later utilized to a great extent by the SPARTAN-IV supersoldiers.
The basic concept for the SPARTAN program has been around since the late 22nd century when the first bioengineering protocols were developed for interplanetary war. Since the establishment of these protocols humans have been using performance enhancing equipment and augmentations to make them stronger and faster than previously thought. These super soldiers have been deployed numerous times throughout human conflict, leading up to and during the Human-Covenant War. The SPARTAN program first arose as a brilliant plan to enhance normal human soldiers into powerfully augmented special operations commandos. Initially the three separate programs were humanity's various attempts to create the perfect soldiers, in order to patrol the colonies, protect civilian and government populations, crush uprisings in their infancy and ensure others don't rise up as a result.
The Spartan soldiers of the UNSC are named after the ancient Spartans of Greece, specifically during the time of the Persian invasion led by Xerxes I. The wars between invading Persians and defending Greeks would be known as the Greco-Persian Wars, and lasted from 499-448 B.C.E.. During this war, the Battle of Thermopylae occurred, in which 300 Spartan soldiers leading 5000 other Greeks under the command of Leonidas I, held back a force of approximately 1 million Persian soldiers although, according to ancient sources, most historians today think that the Persian army was around 100,000 in size although this would still be an enormous force. All of the Spartans were eventually killed, but they successfully killed 20,000 Persians (according to Herodotus), and bought the Greeks time to prepare a better defense for Greece. The Spartans' formidable resilience resulted from their rigorous training in the agoge, which started when they reached the age of 8.
The SPARTAN program began in 2321 with the activation of the ORION project. Launched by the Office of Naval Intelligence, the project was named after the Greek mythological hero Orion. The aim of ORION was to build on bioengineering protocols established in 2164 and create stronger and better soldiers than any before them.
The initial beginnings of ORION were merely a test to see what could be accomplished with the advancements of that time, and candidates of the ORION project were all volunteers from the armed forces of the military - these handful of candidates went through numerous testing and augmentations throughout the duration of the project. However, the results were far less than expected and eventually the candidates were seeded into the regular chain of command after the project was declared ineffective and terminated.
 The Relaunch of ORION (SPARTAN-I Program)
In 2491 the Colonial Military Administration relaunched ORION in secrecy, with the new goal of learning from the mistakes of the previous attempt, and creating a soldier unlike anything seen before - and to deploy these soldiers behind enemy lines and quell insurgencies in their infancy, or destroy established insurgencies by destroying their chain of command and expanding outward.
The project was headquartered in one of the many orbital docks on the fortress world Reach, and the candidates were, once again, selected volunteers from all Special Force branches of the military. This iteration of the project used more advanced indoctrination and biological augmentation techniques, and after a grueling series of physical and mental tests, the first batch of soldiers, 165 in total, successfully passed and moved on to the next phase. In 2496 the UNSC launched Operation: CHARLEMAGNE in response to colonial secessionists who executed a series of attacks on Eridanus II, which resulted in numerous deaths and the kidnappings of civilian and government officials in 2494. This marked the first operational deployment of the ORION soldiers, who scored a decisive victory and emerged from the battle with only a single casualty. The Spartans were able to complete the mission without even being seen, thereby fueling a range of conspiracy theories and media speculation, this proved to be very helpful to ONI's propaganda efforts in the coming decades. Though the Spartans were effective, their abilities fell short of the scientists' hopes, and they cost far too much to develop and field - in 2506 the project was deactivated and the soldiers were reassigned to various special operation units.
 The SPARTAN-II Program
In the years following the deactivation of the SPARTAN Project in 2506, the Insurrection became too large for the UNSC to manage with small Special Forces teams. As the Insurrectionist attacks were becoming more effective, and the military's responses heavier; the need for large scale military campaigns were becoming more and more necessary. The SPARTAN-II project was conceived by Dr. Catherine Halsey of ONI's Section 3, as the successor to the original ORION project and the best possible solution to end the conflict with the Insurrectionists.
In 2517 the project began; whereas the former SPARTANs were chemically-enhanced volunteers from the armed forces, the SPARTAN-IIs were young children, literally kidnapped from their homes, who were indoctrinated and raised as soldiers from as young as six years old, being cybernetically and surgically enhanced once they reach physical maturity. Although it was viewed as wildly unethical and filled with controversy, the secretive program produced results, and more importantly the SPARTAN-II soldiers proved to be the most effective soldiers ever fielded by a human armed force - and the most powerful weapon in the battle against the Insurrection. However, in 2525 the sudden breakout of the Human-Covenant War proved to be the most challenging and daunting war yet waged by humans, and the SPARTAN-IIs were outfitted with MJOLNIR, the most advanced mechanized armor in human history.
While the war with the Covenant continued to progress and the Insurrection was effectively cut off, the SPARTAN-IIs continued to engage Insurrectionist factions who remained strong enough to pose a genuine threat to the UNSC. The SPARTAN-IIs continued to perform their missions near-flawlessly, and ruthlessly killed off rebel leaders while engaging Covenant forces, doing whatever was necessary to protect the interests of the UNSC.
 The SPARTAN-III Program
As the Human-Covenant War progressed and casualties mounted exponentially, ONI activated another program that was arguably even more morally questionable than the SPARTAN-II program. Spearheaded by a prominent opponent to Halsey's SPARTAN-II program, Colonel James Ackerson establishes the SPARTAN-III Program using the previous program as a proof of concept.
Designed to produce supersoldiers more quickly, at a lower cost, and with a lower life expectancy, the SPARTAN-III program is intended for extreme high risk operations conducted at the highest level of secrecy. The SPARTAN-III candidates are once again children, however rather than actually stealing children from their beds, this time the "candidates" were children in their pre- or early teens, recruited from orphanages after the loss of their homes and families from the Covenant invasion, given the opportunity to strike back at the Covenant. The S-III candidates were taken to the planet Onyx and were under the leadership of SPARTAN-II Lieutenant Commander Kurt Ambrose. Throughout the Human-Covenant War, three companies of SPARTAN-IIIs were trained, deployed and killed. The first company of S-IIIs, Alpha Company, was successful in destroying Covenant and rebel forces during the battles of Mamore, New Constantinople and in the Bonanza Asteroid Belt - their last mission Operation: PROMETHEUS in 2537 was deemed a success, even though all of the Spartans of Alpha Company were killed in action. The second company, Beta, was trained soon after the loss of Alpha, their first mission Operation: TORPEDO in 2545 was also deemed a success; however, only two Spartans, Tom-B292 and Lucy-B091, survived out of the three hundred soldiers that took part in the operation. Tom and Lucy became trainers for the third company of S-IIIs, Gamma Company. The third company of SPARTAN-IIIs completed their augmentation and most were deployed on missions elsewhere during the final years of the war, when the Shield World on Onyx was activated.
Smaller, highly specialized units consisting of SPARTAN-IIIs also existed - the Headhunters and Noble Team, the latter so close in effectiveness to SPARTAN-IIs that they received SPARTAN-II-grade MJOLNIR armor and had a SPARTAN-II as a permanent member. Several teams of Gamma Company survived the Battle of Onyx and eventually rescued by UNSC forces. The remaining members of Gamma would be offered to join the SPARTAN-IV program.
 The SPARTAN-IV Program
Conceived by Admiral Margaret Parangosky following the SPARTAN-III Program, the SPARTAN-IV Program was to be headed by Colonel James Ackerson with Dr. Halsey forced to work under him. However, after Ackerson's death at the hands of the Covenant and Halsey's disappearance, the project was initiated under a different leadership. Like the original ORION Project, the SPARTAN-IV Program would use only consenting adult volunteers. The SPARTAN-IVs serve in a dedicated branch of the UNSCDF known simply as "Spartan", whereas their forebears operated within other chains of command.
 Subordinate units
 ORION Project
- Main article: ORION Project
The ORION project or the SPARTAN-I program was first phase of the SPARTAN program, initiated in 2491. The original Spartan project was created to test genetic enhancements on volunteers from the armed forces. Despite a high mortality rate, the ORION project was successful enough to eventually warrant a SPARTAN-II program.
 SPARTAN-II Program
- Main article: SPARTAN-II Program
The SPARTAN-II Program was the continuing effort to produce super-soldiers and would be highlighted by being the first in the series to mix an Advanced Powered Exoskeleton System with the subjects' superior physiques. The SPARTAN-IIs were heavily engaged in the Human-Covenant War. Since the end of the Human-Covenant War, only a handful of survivors remain in active service with the UNSC. The SPARTAN-II Program's official symbol is an eagle posed with its talons forward, ready to strike holding a lightning bolt in its left talon and arrows in its right.
 SPARTAN-III Program
- Main article: Spartan-III Program
Outfitted and engineered by James Ackerson and the Office of Naval Intelligence, the SPARTAN-III program was the next generation of Spartan super soldiers, perfecting and rectifying all that the SPARTAN-II program could not. While they are inferior to the SPARTAN-IIs in terms of general strength, speed, etc, they were designed to be more numerous, better trained, cheaper, and expendable. The few of them with exceptional genes like the SPARTAN-IIs were put into a separate team.
 SPARTAN-IV Program
- Main article: SPARTAN-IV Program
Unlike the previous two projects, the SPARTAN-IV Program was to use adult volunteers only, similar to the I's. The project was already active as of 2553, with some of its personnel serving aboard the prototype warship UNSC Infinity.
In order to preserve morale during the Human-Covenant War, the UNSC promoted the belief that Spartans could not be killed, hence why all deceased Spartans are listed either as Missing in Action or Wounded in Action.
Avery Johnson, a SPARTAN-I.
John-117, a SPARTAN-II.
Noble Six, a SPARTAN-III.
Sarah Palmer, a SPARTAN-IV.
 List of appearances
- ^ Halo: Ghosts of Onyx
- ^ a b Halo Waypoint: Story
- ^ a b c Halo Encyclopedia, page 44-45
- ^ Dr. Halsey's personal journal, June 19, 2513
- ^ Halo Encyclopedia, page 85
- ^ Halo: Glasslands, page 147
- ^ Halo: Glasslands, page 434
- ^ Halo Graphic Novel, page 122
- ^ Halo: The Flood, page 16
- ^ Jan - Axon Clips Chapter 5
- ^ Halo: Glasslands, page 434
- ^ Halo: Glasslands, page 422