ORIGINS:
The SPARTAN-III program was a top-secret project initiated by the Beta-5 Division of ONI's Section Three in order to produce cheap and expendable supersoldiers to stem the tide of the Covenant's onslaught against the Outer Colonies. In active service between 2536 and 2552, the SPARTAN-IIIs turned the tide of several critical battles of the Human-Covenant War. After the war, the remaining SPARTAN-III personnel were given the opportunity to join the newly formed Spartan operations, supplementing the numbers of the SPARTAN-IVs.
The SPARTAN-III project was created as both a successor and supplement to the SPARTAN-II project. The Spartan-IIIs were to be the next generation of supersoldiers. Composed primarily of vengeful orphans from fallen colonies, they would be cheaper to arm, train, and produce; being chosen from a wider pool of candidates, they would also be more numerous than their SPARTAN-II predecessors. They would rely more heavily on teamwork and sheer numbers than advanced technology and equipment to achieve effectiveness.

SPARTAN-III COMPANIES:
In 2531, the first group of SPARTAN-III candidates were sent to be trained at a pre-discovered Forerunner Shield World designated: ONYX. This group was known as ALPHA COMPANY. They were trained by a SPARTAN-II and 300 of these 400+ candidates successfully became Spartans. Their record on a number of engagements was exemplary. Nine months after activation, Alpha Company was deployed on Operation: PROMETHEUS, a mission to destroy a Covenant shipyard on an asteroid. 
All 300 Spartans deployed on the mission were killed. Some select members of this group were extracted prior to the operation to be re-assigned.

BETA COMPANY was approved right after Operation: PROMETHEUS in 2537. 418 candidates were conscripted in 2539, from whom the final company of 300 was formed. Disheartened at the loss of Alpha Company, the SPARTAN-II training them used a tougher training program and more thoroughly trained them in unit cohesiveness. Despite their superior training, they were similarly massacred in Operation: TORPEDO in 2545. From the entire company, only two participants survived the battle. Similarly to Alpha Company, a select few members were re-assigned from the group prior to the company's final engagement.

GAMMA COMPANY was trained with the help of the only two Spartan-IIIs from Beta Company who survived Operation: TORPEDO. Described by their SPARTAN-II trainer as the "finest" company to date, 330 candidates were selected, on average only six years old, and at their trainer's request all 330 were approved for graduation. Gamma Company received deployment orders only a few weeks after the Fall of Reach and most left Onyx. Only fifteen SPARTAN-IIIs of Gamma Company remained on Onyx as they competed for top honors. Following the battle, seven had been killed in action. Team Saber was the only Gamma Company team to fight alongside the SPARTAN-II unit "Blue Team". With the help of their older, more experienced counterparts, they successfully fought off a Covenant attack along with destroying a Sentinel Manufacturing Facility. Ultimately, the surviving SPARTAN-IIIs escaped to the Shield World at the core of Onyx

SPI ARMOUR:
Semi-Powered Infiltration armor (SPI) was the primary armor system used by the Spartan-IIIs. Though more advanced than the ODST combat suit, it is considerably less powerful than the MJOLNIR armour. The main benefit was that the SPI armour was significantly cheaper to produce than MJOLNIR armour. The armour's design was based more around stealth than raw power. It's photo-reactive panels mimicked the user's environment in a form of near-invisibility or active camoflauge. However this effect would be momentarily disrupted if the user took damage. Unlike the MJOLNIR armour, the armour lacks energy shielding and while having a certain degree of resistance to ballistic weaponry, a single hit from a plasma weapon can burn the photo-reactive panels and render the armour's camoflauging technology useless.


PROJECT CHRYSANTHEMUM:
This was the codename given to the biological augmentation procedures performed on the SPARTAN-III candidates. The augmentations were similar to those performed on the previous SPARTAN-II candidates but much cheaper, easier to carry out and with a 0% mortality rate, yielding almost the same results.
One significant difference was the inclusion of three additional drugs that had been outlawed by the UNSC. The first altered key regions of the candidate's frontal lobe to increase aggressiveness in response to stress during combat. The animal part of the brain would became more accessible at this point and candidates would be able to access enormous reserves of strength, speed and endurance and continue fighting even after receiving severe injuries that would prove fatal for normal humans.
The other two drugs were administered to counteract the effects of the first drug.

Approved!