From Halopedia, the Halo wiki
Isaac was conscripted with 74 other children into the SPARTAN-II program in 2517. He was abducted from his home and replaced with a flash clone. He was then taken to Reach, where he was trained with the rest of the SPARTAN-II candidates by the AI Déjà and Chief Petty Officer Franklin Mendez.
Fall of Reach
During the Fall of Reach in Summer 2552, he was assigned to Red Team, under the command of Frederic-104. As part of Red Team, Isaac was assigned to defend the planetside generators that supplied power to the orbital defense platforms. As Red Team descended, their Pelican dropship, Bravo 001, was attacked by Covenant Seraphs, killing the pilot and forcing the SPARTANs to jump from the craft. Both of Isaac's arms were dislocated, which hampered his fighting ability severely.
He was then assigned to Team Delta, under the command of William-043, to secure the SPARTANs' fallback position in CASTLE Base. Vinh, Will, and Isaac were separated from the surviving Marines of Charlie Company, but they eventually arrived at CASTLE Base. They were unable to enter the facility until Fred and Kelly met with them and Kelly whispered the Oly Oly Oxen Free code into the entrance's speakerbox. Dr. Catherine Halsey, the creator of the SPARTAN-II program, then opened the door for them. Isaac was treated by Dr. Halsey and sent to survey the facility's perimeter defenses along with Vinh. This proved unnecessary however, as the Covenant attacked immediately.
Vinh, Isaac, Fred, Kelly, Will, and Dr. Halsey were trapped under CASTLE Base on Reach for several days after Halsey initiated Operation: WHITE GLOVE to destroy the base and keep it from falling into enemy hands. Isaac was able to upgrade his Mark V MJOLNIR armor with parts salvaged from the base. He received a new image-enhancing computer that was in the process of being field-tested and had yet to be certified. After Fred discovered a massive room containing a strange Forerunner crystal, the crystal sent a massive radiation spike that allowed the Covenant to triangulate the group's position. A Covenant Gravity lift quickly appeared, and Isaac and Vinh were ordered to take a rearguard position. Isaac and Vinh dropped back and opened fire until the group retreated toward a nearby tunnel, after which the two Spartans dropped satchel charges to cover the group's tracks. The charges prematurely detonated, causing Isaac and Vinh to disappear. They could not be raised on the COM. In accordance with Office of Naval Intelligence protocol, Isaac was listed as missing in action, but is presumed killed in action.
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