In 2502, UNSC NAVSPECWAR, specifically Project: ORION, sent a young, but capable Corporal Avery Johnson to assassinate Jerald Mulkey Ander, a leader of the People's Occupation Government. The UNSC sent Johnson to Harvest, which, at the time, was a new colony, to assassinate him. This operation was also Johnson's final test for the Naval Special Warfare Sniper School.
Johnson acquired a position a fair distance from his target and set up an M99 "Stanchion" rifle. Johnson was accompanied by another UNSC Marine, presumably his spotter for making calculations for wind and distance.
When Ander's truck passed by, Johnson took the shot and successfully killed Ander, effectively ending the threat posed by the Secessionist Union.