From Halopedia, the Halo wiki
The SPARTAN-IV program is the fourth iteration of the SPARTAN supersoldier projects. Like the original ORION Project, the SPARTAN-IV program utilizes consenting adult volunteers selected from the other branches of the United Nations Space Command, in contrast to the previous two programs which used children as candidates. Recruits are drawn from both career military veterans and young soldiers who show considerable promise.
The physical augmentations of the Spartan-IV supersoldiers are significantly less extensive than those of the two preceding programs, although their standard-issue GEN2 Mjolnir armor is more technologically advanced, and designed to compensate for this drawback. The Spartan-IVs serve in Spartan Operations, an independent branch of the UNSC Armed Forces created for the oversight of their operations.
The SPARTAN-IV program has its roots between 2548 and 2550, when ONI began to experiment with adding limited enhancements to select groups of special operators. After Victor Gallardo, Dorian Nguyen, Evie Rousseau and Saskia Nazari were exposed to the deadly effects of a Forerunner artifact, ONI offered them the chance to become part of the program, having discovered that Owen-B096's genetic enhancements as a Spartan-III made him immune to the same effects. With the dying Victor's parents having already agreed on his behalf, ONI started the augmentations before they told the other three which appeared to be working. After considering their options, the rest of the group agreed to undergo the augmentations and join the new program, both to survive and to continue fighting the Covenant.
At some point prior to the instatement of the current SPARTAN-IV program in 2553, elements within the Office of Naval Intelligence's Section III authorized a prototypical phase without approval from High Command. This incarnation was intended to produce supersoldiers whose physical prowess rendered MJOLNIR armor redundant. However, only one of the ten volunteer test subjects survived the augmentation process. The survivor, Ilsa Zane, was driven mad by the experience and was folded into ONI. Despite the project's failure, Zane was considered the original Spartan-IV.
The program as it now exists was commissioned as a result of the success of the preceding SPARTAN-II and SPARTAN-III projects. The SPARTAN-IV project was conceived by Lieutenant Commander Musa-096, a former Spartan-II candidate who was crippled by the augmentation process. Despite his grudge toward Dr. Catherine Halsey, Musa recognized the crucial role of the Spartans in defending humanity and the continued importance of the supersoldiers in the aftermath of the Human-Covenant War. The proposal was approved by Admiral Margaret Parangosky, then-Commander-in-Chief of the Office of Naval Intelligence, and the new program was initiated under her orders. Parangosky initially planned to have SPARTAN-III lead Colonel James Ackerson heading the program, with SPARTAN-II project lead Dr. Catherine Halsey to be reassigned as Ackerson's subordinate. Ackerson was killed following the Battle of Mare Erythraeum and Halsey was arrested after returning from Onyx, though ONI continued the program without the two, headed by Musa-096 and Jun-A266, a former SPARTAN-III Alpha Company member.
The first class of Spartan-IVs, consisting of 145 members, went active on January 7, 2553. Due to the success of the initial group, Commander Musa-096 was able to secure funding for a second class. Initiated in 2554, the second class was considerably larger than the first one due to the increased funding and was able to draw from a wider pool of candidates.
Facilities and organization
The SPARTAN-IV program is headquartered at a dedicated facility on Mars. Their augmentation procedures are conducted at the same facility. The compound is able to augment around a dozen or two Spartans at any given time. Their training is primarily conducted in a top-secret space station orbiting an unidentified dwarf planet.
Hundreds of Spartan-IVs are assigned to UNSC Infinity, the most powerful warship ever constructed by mankind. The frigate UNSC Meriwether Lewis also has its own Spartan contingent. Spartan-IVs train with one another in simulations known as "War Games" on Infinity's state-of-the art combat deck (a training chamber that is capable of replicating environments), in order to constantly stay battle-ready. Spartan-IVs also train in multiple different forms of martial arts outside of the War Games simulator. As per STO 11.6, Spartan daily training must include at least two hours of military occupational specialty training, and two hours of physical conditioning and augmentation monitoring.  Select Spartan-IIs have participated in the training of the Spartan-IVs.
The Spartan-IVs serve in a dedicated branch of the UNSC known as Spartan Operations or "Spartans", whereas their forebears operated within other chains of command, although some Spartan-IVs serve in more covert roles within ONI. In addition to the significant numbers of adult volunteers which make up the majority of the Spartan-IVs, the Spartan-IIIs who survived the Human-Covenant War were offered to be integrated with the Spartan-IVs in the new Spartan branch. Many of the remaining Spartan-IIIs were folded in with the Spartan-IVs in the new branch, while others resigned to noncombat roles.
Unlike their predecessors, the Spartan-IVs are identified by their surnames rather than numeric tags (due to their volunteered enlistment rather than conscription). The Spartan-IVs have shown a great deal of solidarity, especially impressive given the short time they have served together. Many of them have adopted colloquialisms first used by the Spartan-IIs, such as "Alpha Bravo" for "Alien Bastard". Psychologists assert that this camaraderie and cohesiveness will help distinguish the Spartan-IVs, and the Spartan branch as a whole, from the other UNSC branches.
List of SPARTAN-IV units and personnel known
Ten Spartan-IV candidates were discharged from the prototypical phase of the program after being crippled or killed by the augmentations.
Spartan-IVs are equipped with the MJOLNIR [GEN2], the second-generation version of the MJOLNIR Powered Assault Armor. Because of the Spartan-IVs' less extensive biological augmentations, the GEN2 armor boosts its wearer's reactions, speed, and strength to a greater degree than the first-generation Mjolnir.
An assortment of armor configurations are available for all new Spartans per UNSC Regulation 3A-950, and Spartans are capable of customizing their individual armor set with modular components from a wide range of special-purpose variants, based on their personal preferences, specialization and mission requirements. Selecting variants for purely cosmetic reasons is discouraged. It is strictly forbidden for Spartans to attempt to repair or modify their armor; all armor maintenance is only to be performed by qualified Class-61 technicians in dedicated facilities. Unlike the generally green coloration of the Spartan-IIs' Mjolnir armor, Spartan-IV armor comes in a profusion of distinct color patterns, with the members of specific teams often sporting a consistent coloration. However, any customization of the armor color must be in accordance to UNSC Equipment Code 20.00.62.
The standard-issue armor set for Spartan-IV (at least those assigned to UNSC Infinity) is the Recruit variant, colored gray and gold. Spartan-IVs also have access to more specialized equipment depending on their missions, example being the Infinity Actual Kit, and Forerunner Hybrid Kit.
Like the augmentations performed for the Spartan-IIs and the improved procedures utilized in the subsequent SPARTAN-III program, the Spartan-IVs undergo a series of procedures to enhance their physical capabilities and to wear Mjolnir powered armor. The technology used in the two preceding SPARTAN programs necessitated that the candidates meet exceedingly strict genetic qualifications as well as the application of the enhancements on preteens, to avoid the catastrophic failure rates produced by the augmentation of adult subjects in the ORION Project. By the time of the initiation of the SPARTAN-IV program, the technology had advanced to the point that adults could be augmented without major risk, although the improvements to the subject's strength and speed are not as extensive as in the previous two programs.
List of appearances