Spartans play a major roll in the Halo universe. They are genetically modified super-soldiers built and trained to guarantee success in key battles in the war between the UNSC (United Nations Space Command) and the Covenant empire (alien alliance). Spartan training starts with the kidnapping of handpicked seven year old children who are replaced with biological clones that die within a month due to an implanted disease to assure there is no public record of the event. Once taken from their homes, they are shipped to planet Reach, one of the UNSC’s most treasured military planets. There, they are then introduced to Doctor Catherine Elizabeth Halsey, the scientific adviser for ONI (Office of Naval Intelligence) and lead scientist in the Spartan II Program. The Recruits start Boot camp with an early wake-up time (5:30), showers, PT, and an electric baton to encourage those who are slow.

Years after their arrival, they are all given a mock operation and are separately dropped off with a different piece of a map leading to the LZ. Towards the end of training, the soon-to-be Spartans go through physical and mental augmentations. After the augmentations, the Spartans are then moved to an abandoned Titanium Mine to keep their existence a secret. After boot camp Spartans are given MJOLNIR power armor. MJOLNIR armor enhances strength, sight range, movement speed, and reaction time. Once given the armor, they are then given additional training on how to use the armor to the best of its abilities.

The Spartan II project took near 8 years and was shut down due to high living cost and inhuman tactics of indoctrination. In later years, the program was re-instituted into the UNSC as the Spartan III and Spartan IV programs. However, they used less intense tactics of training and tweaked the effects of augmentation trading power for safety.