"You need a weapon?"
Jhon 117 or most commonly called the master chief is a cypernetic soldier known as a spartan.When the prophets ordered the covenat to glass Pocketville, He and a group of marines where called in to help help,now pocketville is teamed up with the unsc to stop the prophet of truth.
John was born in about 2511 and lived with his mother and father in Elysium city on the colony world of Eridanus II. He attended the Elysium City Primary Education Facility Number 119. As a child, John had brown hair, freckles, and a small gap between his front teeth. In a dream during cryo-sleep aboard the UNSC Pillar of Autumn, John recalled that his mother was "kind and smelled of soap," and that she had "large eyes, a straight nose and full lips." The would-be UNSC Marine Lieutenant Parisa was a childhood friend of John's who John once saved from drowning at Lake Gusev; John thereafter promised to marry and protect her. Parisa's father shot a photo of the two soon after that Parisa kept as a memento long after she thought John had died.
Dr. Catherine Halsey identified John as an ideal physical and mental candidate for the 150-strong preliminary pool of the SPARTAN-II Program when he was six: he stood a head taller than the majority of his schoolmates, had greater physical proportions, and possessed greater strength, superior reflexes, and an aggressive drive for success. When Dr. Halsey and Lieutenant Jacob Keyes visited Eridanus II in 2517 to study him, they were impressed with his intellect and luck. In a final test of his viability as a candidate, he was asked to determine which side an old coin would land on. He watched the coin as it flew in the air and caught it before it could land, correctly stating which side was face-up and which was the side of the eagle. John was the first candidate Dr. Halsey and Lieutenant Keyes studied. Later that same year, John and 74 other six-year-old children were "conscripted": they were covertly kidnapped from their homes and replaced with flash clones, all of which would later die of natural causes to cover up the kidnappings. John, along with the other candidates, was taken to the planet of Reach. Dr. Halsey informed them of the SPARTAN-II Program and how they would be "the protectors of Earth and all her colonies." The next morning John discovered his service tag, stitched into his training uniform, and his new name: John-117.John began a new life. He trained with other Spartans under Chief Petty Officer Franklin Mendez. For eight years he learned history, military strategy, weapons and received physical fitness training. Early on, he bonded with Kelly and Sam, who would become two of the few close friends that he would ever have.(info from halo wikia)