The SPARTAN-IV Program was the fourth generation of the SPARTAN Program consisting of members recruited from the UNSC's various branches who were augmented to be capable of wearing a new variant of the MJOLNIR Powered Assault Armor (GEN2) armor. This phase was initiated by Admiral Margaret Parangosky after the Human-Covenant war.
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 Powered Assault Armor (GEN2) armor to enhance the Spartan's abilities even more than that of MJOLNIR GEN1 armor.
Sometime prior to the public iteration of the SPARTAN-IV program, ONI Section III authorized a top secret, experimental phase of the program, without direct permission from High Command. This variation of the program would attempt to produce super-soldiers whose physical prowess rendered MJOLNIR obsolete. Only one of the ten candidates, Ilsa Zane, survived the augmentation process. She was considered mentally unstable due to the augmentations and was forced deep within the layers of ONI.
The current SPARTAN-IV program was commissioned due to the success of the SPARTAN-II and SPARTAN-III Programs. The program was initiated by Musa-096, a washout of the SPARTAN-II program's augmentation process. Even with his resentment for Dr. Catherine 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 AdmiralMargaret Parangosky, when she was still in command of the Office of Naval Intelligence. At first, Parangosky wantedJames 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 andJun-A266, a former member of the SPARTAN-III Alpha Company.
In addition to the majority of the SPARTAN-IVs being adult volunteers, all remaining SPARTAN-IIIs were offered to be incorporated into the Spartan branch. Many of the remaining SPARTAN-IIIs were fitted into the Spartan branch while the rest were moved to non-combatant status. The first class of SPARTAN-IVs consisted of 145 individuals and went active on January 7, 2553. 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.