It all started with ONI, in their attempts to fight the Insurrection. They decided to find volunteers among the soldiers in order to turn them into better soldiers. The members of the ORION Program (later known as the SPARTAN-I Program) were all augmented soldiers, using new training methods and the latest breakthroughs in biochemical developments to not only improve the soldiers physically, but also mentally; mental augmentations were performed to enhance brain functions. All 65 initial volunteers made it through the training and augmentation procedures and were placed on active duty sometime after completing their training. After their initial deployment and success funding for training the next group of SPARTAN-Is was approved, and within a few years the SPARTAN-I Program had 165 active duty personnel.
Many SPARTAN-Is were deployed to take down insurrectionist strongholds, but one of the key goals was to eliminate Jerald Ander, the leader of another major insurrectionist faction, the Secessionist Union. Although Operation: KALEIDOSCOPE successfully dealt a heavy blow to the insurgents, the overall strategy of KALEIDOSCOPE failed to pacify the colonies. Operation: TANGLEWOOD would be the last operation the SPARTAN-Is participated in, the exact nature of this operation is not known other than that it was to combat insurrectionist forces. In 2506 The SPARTAN-I Program was quietly deactivated and the surviving members reassigned to other special operations units in the field. However these soldiers often exhibited side effects as a result of their augmentations and many members were discharged from the military as a result of mental instabilities. In order to ensure absolute secrecy, the side effects caused by SPARTAN-I augmentations are masked as a disease known as Boren's Syndrome — many SPARTAN-Is go on to retire, some eventually have children, but due to their augmentations their children must also be given some form of injections to ensure no defects.
You will become the best we can make of you
About a decade later, after the failed attempt to enhance extraordinary soldiers in true, long-time, supersoldiers, the Insurrection movement had spread and had become a great force. When in 2517, ONI concluded that by 2525 the war against the Insurrection would be lost, they gave Dr. Catherine Halsey permission to start up her SPARTAN-II Program to create the supersoldiers ONI desired. Halsey's proposal for the project detailed radical changes in many different fields. The first and most controversial was the subjects themselves, who were selected by a gene-candidate pool, and fit into a certain age restriction protocol (six years old). They also possessed superior physical and mental attributes when compared to other children their age. This narrowed the candidates down to children who would be raised and taught in the art of warfare and military values from a young age, which cannot be taught to older enlisted personnel. Using such controversial means of creating a soldier meant that the project would have to be carried out under the highest levels of secrecy.
The second radical change involved integrating the subject with a new powered exoskeleton device, designed to help keep its user safe and provide a powerful means of combating enemy forces. The drawback of this new armour is its requirement for augmenting the subject, effectively turning the SPARTANs into human guinea pigs.
The first ever 75 SPARTAN-II subjects were sent to the world Reach and began training under CPO Mendez. During the hardships of these 5 and 6-year olds, they were placed in hazardous situations which would put them to their physical limit, partnered with high-level education including mathematics, science and military tactics. Although his training methodology was tough, even brutal in some regards, Chief Petty Officer Mendez always instilled discipline, honour, and respect into the SPARTANs. He taught the SPARTANs how to kill, but at the same time he taught them the difference between right and wrong. Mendez trained the SPARTAN's until 2525 when, at the age of fourteen, they would go through the toughest part of their training: the biological augmentation procedures, which would kill 30 of the 75 conscripted children and cripple 12 others who would "wash out" of the SPARTAN-II program.
One of these crippled SPARTANs was Soren-066, his body did not react as planned to the muscular enhancement injections and the thyroid implant, which had caused his muscles to grow in ways that were unpredictable. Only by using the carbide ceramic ossification process was he saved. One leg was more or less normal, if a little bowed and twisted, however the other was severely gnarled and about six inches shorter. His arms were incredibly muscular, painfully so, giving him the greatest upper body strength of any Spartan. The fingers of one hand were twisted and bowed, functioning more like a pincer or claw. To deal with the intense pain Soren was given massive amounts of painkillers, however he did not like the way they clouded his mind, so he gradually weaned himself off them. After his somewhat recovery, there was nothing they could do against his deformities, he was giving, against his will, a desk job. Here he met the Insurrection-sympathist Partch who slowly turned Soren sympathetic as well. After several months of this, Partch and Soren infiltrated a geological research lab, but where stopped by the SPARTAN-II Randall-037. After Randall had been subdued, Partch and Soren fled on an aircraft, but were followed and engaged. After the aircraft had been sufficiently damaged, they crashlanded, killing Partch in the crash. Soren fled the scene, and has not been seen since.
Die? Don't you know? Spartans never die.
But not all SPARTANs had such a tale, at least not the most famous SPARTAN-II of all, John-117, whom I have already discussed in length in my inaugural Halo 101. The SPARTANs had to learn everything again, from simple movements to using their eyes. After sufficient time to recover, the SPARTAN troops were deployed against the Insurrection,
When the UNSC encountered a new threat, the Covenant, all SPARTANs that were deployed against the Insurrection were sent to battle them. Partnered with their new MJOLNIR armour, they were deployed on numerous missions. Many of the Insurrection rebels, seeing that the UNSC offered the only real protection against the overwhelming Covenant force, ceased to resist, and either submitted to the UNSC's control or hid themselves away from both UNSC and Covenant. As the exploits of the SPARTANs were a major propaganda boom to the UNSC, Section II of the Office of Naval Intelligence issued Directive 930, which stated that SPARTANs killed or wounded would be listed as "Missing in action" (MIA) or "Wounded in action" (WIA), thus maintaining the illusion of the SPARTANs' invincibility.
In an attempt to force the Covenant into a cease-fire, they were to commandeer a Covenant vessel, locate the Covenant homeworld, and return with captured Covenant leadership to force a ceasefire. The Artificial intelligence construct Cortana, carried within John-117's Mark V MJOLNIR armour, would serve as the strike force's hacker and technology specialist. However, all preparations were interrupted and subsequently cancelled by the Covenant's invasion of Reach. In the ensuing disaster, most of the SPARTAN-IIs were killed, while some took shelter in ONI's CASTLE Base. Two escaped aboard the UNSC Pillar of Autumn, one of whom was place in cryostasis aboard the ship after sustaining life-threatening injuries during the battle on Gamma Station. The Pillar of Autumn soon arrived at Halo Installation 04, which John-117 ultimately destroyed to prevent the spread of the Flood. Following the Battle of Installation 04, the survivors returned to Reach and were able to rendezvous with the remaining SPARTANs. The survivors then carried out a raid that resulted in the destruction of a Covenant fleet anchorage, stalling a Covenant plan to invade Earth. SPARTAN-IIs would go on to play pivotal roles in the Battle of Earth, the Battle of Installation 05, the Battle of Onyx, and the Battle of Installation 00.
Make more of them. And make them cheaper.
The SPARTAN-IIs were by far the best fighters the USNC had to offer, and after they became public knowledge, they would serve as a morale boost for the entire human race. But there were also problems, for one, the Program was too expensive. The SPARTAN Program, including their training and Mjolnir Armor, cost as much as a Battle Group. But worst problem was that the 75 active SPARTAN-IIs were too few. New recruits were difficult to come by, as Dr. Halsey required only children with "perfet genes". In order to compensate for this, the SPARTAN-III Program was started under Colonel James Ackerson
The SPARTAN-IIIs were designed to be cheaper and expendable. They would be trained in companies of 300 to 330 at a time, with a training regime tougher than that of the previous Spartan Program. They were sent on suicide missions that the UNSC could not accomplish with a conventional invasion force, elite Orbital Drop Shock Troopers, or even SPARTAN-IIs. Though the casualty rates of the SPARTAN-IIIs stood at 100 percent on some missions, to ONI, all the operations were strategic successes. They were trading lives for time against the larger and technologically superior Covenant Empire. ONI hoped that in time, enough Spartans would survive to train more and more future Spartans, swelling the ranks of available super soldiers from only thirty SPARTAN-IIs in 2531 to a hundred thousand SPARTAN-IIIs within ten to twenty years.
The first group of Spartan-IIIs, known as Alpha Company, were sent to Onyx to be trained at Camp Currahee. They were led by Kurt-051 a SPARTAN-II operating under the pseudonym "Ambrose". Of the 497 candidates who were conscripted, only 300 became Spartans. This class of Spartans all survived the augmentations and was activated in November of 2536. Their record was at first exemplary, as they saw action at the Insurrection of Mamore, the Battle of New Constantinople, and at the Bonanza Asteroid Belt. Nine months after they were activated, they were massacred in Operation: PROMETHEUS. All of the three-hundred Spartans deployed on the mission were supposedly killed. Beta Company was approved right after Operation: PROMETHEUS which produced another 300 SPARTAN-IIIs. But when all 300 were sent to Operation: TORPEDO, all but Tom-B292 and Lucy-B091 were killed.
After the massive losses, but both tactical victories, of the first two companies, another batch of future SPARTAN-III soldiers were admitted. All 330 candidates survived their training and augmentations, together with illegal drugs that altered the frontal lobes of their brains to enhance aggression, strength, endurance, and tolerance to injury. These SPARTANs received deployment orders only a few weeks after the Fall of Reach, and most left Onyx before the Battle of Onyx occurred. It is unknown where they presently are.
We're back to using consenting adults now, like we did in Project Orion.
Similar to the original ORION Project, the SPARTAN-IV Program would only consist of adult volunteers as opposed to young children. When the program was started, surviving members of previous Spartan generations were offered an opportunity to be integrated into it. SPARTAN-IV recruits are drawn from active combat veterans of any branch as well as young soldiers who show potential to be Humanity's next guardians. The physical augmentations of the SPARTAN-IVs, while more advanced than their predecessors, still cannot produce similar results without risk of a high failure rate, due to no genetic requirements. This drawback is reconciled by modifying the individual to the closest margin possible of the two previous Spartan programs physical results and then relying on MJOLNIR GEN2 armor to enhance the Spartan's abilities even more than that of MJOLNIR GEN1 armor.
The current SPARTAN-IV program was commissioned due to the success of the SPARTAN-II and SPARTAN-III Program. The program was initiated by Musa-096, a washout of the SPARTAN-II Program's augmentation process. Even with his resentment for Dr. Halsey, Musa recognized the importance that SPARTANs had in the effort of protecting humanity, even after the Human-Covenant war. The SPARTAN-IV program was approved by Admiral Parangosky, when she was still in command of ONI. At first, Parangosky wanted James Ackerson to head the program with Halsey by his side. However, Ackerson died during the aftermath of the Battle of Mare Erythraeum and Halsey was arrested after returning from Onyx. The program was continued by Musa and Jun-A266, a former member of the SPARTAN-III Alpha Company.
They trained with each other in War Games simulations in order to be constantly prepared for battle. SPARTAN-IVs also train in multiple different forms of martial arts when not active in the War Games simulator. Select SPARTAN-IIs who were thought to be MIA have also participated in their training. But even with this training, Dr. Catherine Halsey considers SPARTAN-IVs to be inferior to SPARTAN-IIs since they haven't undergone a lifetime of military training and indoctrination.