From Halopedia, the Halo wiki
The key to the SPARTAN-IIs' seeming invincibility and matchlessness in combat has always been their training, honing their finesse even outside of wearing MJOLNIR armor, and, combined with their augmentations, making them superior in strength, speed, accuracy, reaction times, and intelligence to all other UNSC military personnel. Headquartered in a dedicated compound within the FLEETCOM Military Complex on Reach, the Spartans' training was mainly orchestrated by Chief Petty Officer Franklin Mendez, with the AI Déjà providing theoretical education in the Reach Naval Academy.
During their first years of training, the Spartans were placed into situations and drills that pushed their abilities to their very limit and beyond. Their hard training was complemented with high-level education, which included mathematics, science, history, reading, writing, and military tactics. Although his training methodology was tough, even brutal in some respects, CPO Mendez always instilled discipline, honor, and respect into the Spartans. Over the course of their years of training, the Spartans learned and developed a unique system of signals for use among themselves. During this time, John-117 rose to be the de facto leader of the Spartans, with Kurt-051, Jerome-092 and Frederic-104 identified as other emerging leaders.
The Spartan often trained in various locations across Reach's Highland Mountains surrounding the FLEETCOM compound; among these were Camp Hathcock, Military Reservation 01478-B and the Military Wilderness Training Preserve. They were also taken to various offworld sites for specialized training, including Emerald Cove and the Chiron extreme-conditions facility over Mars.
Between 2511 and 2517, 150 five to six-year-old children were selected from near perfect psychological and genetic markers that were set in Dr. Catherine Halsey's selection protocols. The children were screened for certain genetic markers: strength, agility, even predispositions for aggression and intellect. But due to lack of facilities and funding, only 75 children were chosen for the program. The other half of the 150 original candidates were "weeded out" possibly through chance luck, the single flip of a coin.
Between August 17 and September 23, 2517, the accepted candidates were taken from their homes in the middle of the night, injected with a sedative, and rushed through slipspace to Reach, where they were going to be trained. They were only recently brought out of cryo-sleep when they were introduced to the program in the Reach FLEETCOM Military Complex, which would become their new home for several years. In the secure briefing chamber of the complex, Dr. Halsey told them that, in accordance with Naval Code 45812, they would be indoctrinated to defend Earth and all her colonies. She attempted to encourage them in spite of the fact that they could not return to their parents and would be forced to endure many hardships in the years to come. The children were then escorted to barracks where they had a meal, and went to bed at around 2330 hours.
September 24, 2517
The Spartans were awakened early in the morning by CPO Franklin Mendez and his instructors at 0530 hours. Mendez ordered them to go to the showers and those who hesitated were hit with an electric baton. Once outside, CPO Mendez ran them through 100 reps of jumping jacks, sit ups, deep squats, push ups, and leg lifts.
Afterwards, Mendez and the instructors jogged them about a mile to the Reach Naval Academy where Déjà, a "dumb" AI and Halsey's attaché on the program, taught them a wide variety of lessons, including mathematics, science and history, between physical training. Their first lesson was a video of the original Greek Spartans fighting against Persian soldiers at Thermopylae. Then they jogged two miles to the "playground", a maze in mid-air with a bell at the top, where they were divided into teams of three. Each team was tasked to ring the bell positioned on a pole and then cross the finish line. The last team to reach the bell at the end would not get supper, as an incentive to win. Though John-117 reached the bell first, his other team-mates were last, forcing them all to do without supper.
September 25, 2517
The Spartans were woken, took their showers and did their morning calisthenics and ran a mile to Déjà. Their lesson was about a pack of wolves hunting moose. After the lesson they ran the two miles to the playground, which had been changed and was much more complicated.
September 26, 2517 - July 11, 2519
In this time Mendez taught them to strip a trip line, fire a rifle, and treat a chest wound. Mendez's exercises often had a twist to them such as stun mines on the obstacle course, snipers with paint guns during parade drills, and others. They were taught to be strong in body and mind.
July 12, 2519
Two years later, Mendez took them to a training mission in the Military Wilderness Training Preserve. Pieces of paper were distributed, fragments of a map of the local region that had been shredded. They were set down alone to navigate to the marked extraction point and picked up there by an Albatross dropship. They were told that the last one to the extraction point would be left behind and have to walk back.
Instead, however, the Spartans combined their strengths to meet up together at a lake near to the LZ. They discovered an Albatross dropship, as promised, but the occupants were not in uniform and carried live-ammunition weapons. The Spartans lured the men into an ambush, either knocking them out or killing them. They then hijacked the Albatross and John contacted Déjà, who remotely piloted the dropship back to base. John made sure he was last to board the Albatross to make sure that nobody else would have to walk home.
John was made team leader for his planning of the Spartans reaction to the training operation.
During the Spartans' third year of training, they studied classical mechanics in the physics courses, though John-117 was more interested in tactical theory than Newton's laws of motion.
July 14, 2523
For even more serious training, the Spartan-IIs were matched against the formidable Tango Company in simulated war games. Still only 12 years old at the time, the Spartans were nevertheless able to continuously beat Tango Company. Eventually, the men of the company resorted to brutality as a form of payback, with "accidents" occurring with Spartans captured in the war games. Eventually, Tango Company's CO, furious at his men's inability to stop the Spartans, ordered them to use live rounds instead of stun rounds.
September 11, 2525
The newly augmented Spartans were transferred to an abandoned titanium mine on Reach to enhance secrecy and reduce the injury risk to other personnel. Due to the uneven strength, speed, intelligence and accuracy of the Spartans, their trainers were forced to don Mark I powered armor simply to keep up with them. Training missions invariably ended in a victory for the Spartans, with even security cameras neutralized.
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