From Halopedia, the Halo wiki
Sergeant Major Nolan Byrne (service number 48780-19114-NB) was a UNSC Marine and a possible SPARTAN-I. He took part in Operation: TREBUCHET with Avery J. Johnson, until he was severely injured by an insurrectionist bomb. Byrne was then reassigned to the planet Harvest to train the local militia with Johnson.
Byrne was born in Ireland, on Earth at some point during the twenty-fifth century. While his life prior to his involvement in the Insurrection is largely unknown, it is known that he was familiar with Avery Johnson before working with him in Operation: TREBUCHET.
During the Insurrection, then-Staff Sergeant Byrne participated in Operation: TREBUCHET in 2524 leading Bravo Squad of a platoon of NAVSPECWAR marines alongside Staff Sergeant Avery J. Johnson. Their squads used Hornets to conduct air assaults on multiple targets in efforts to eliminate Rebel bomb-making factories. However, when a rebel (armed with a bomb) was cornered in a Jim Dandy restaurant, Byrne told Johnson to fire a M99 Stanchion Gauss rifle at an Insurrectionist holding a child hostage. Johnson did not have a clear shot at the rebel, which led to the boy's father tackling the female rebel, who then detonated her explosives, destroying the Jim Dandy restaurant and killing most of the Marines in Byrne's squad plus thirty-eight civilians.
Battle of Harvest
After recovering from his injuries, Byrne was reassigned, along with Johnson, to train the Colonial Militia on Harvest. He had felt great resentment at Johnson's hesitation on Tribute, and picked a fight with him as soon as he arrived on Harvest. Byrne had almost killed Johnson if Captain Ponder had not intervened. Their actual mission was to create a covert anti-insurgency unit, as revealed by ONI officer Lt. Cdr. al-Cygni, and to lay an ambush on insurgent forces suspected in the disappearances of DCS freighters around Harvest. However, he and Johnson fought four Jackals in the first battle between the UNSC and Covenant, on board a human freighter, and they successfully defeated them. Byrne and Johnson (with the rest of the militia of Harvest) were also present at the initial negotiations between the Jiralhanae and the humans. They also fought Tartarus, Maccabeus and several Grunts. One militia soldier was torn apart by a Grunt, which sparked the firefight. As the conflict heated up, Byrne continued to defend the planet from Covenant hostiles and he received multiple injuries in the conflict. He managed to live through the battle, and was evacuated with Johnson, Jilan al-Cygni, and the rest of the Colonial Militia in a pod heading from the Tiara.
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