The Siege of Paris IV was an engagement between the United Nations Space Command and the Covenant Empire on the UEG colony world of Paris IV in the Paris system. It took place in 2549. The then-Sergeant Avery Johnson received a Commendation for Bravery during the mission.
According to the Office of Naval Intelligence, Johnson and his Marines had captured a crate of Plasma grenades and held off the Covenant forces at the main evacuation complex long enough for the evacuation ships to leave and get into orbit. The Plasma Grenades Johnson had captured exposed him to a deadly amount of radiation but he survived, ostensibly contracting Boren's Syndrome. Note that Boren's Syndrome is actually a fictional disease, fabricated by ONI to cover up Johnson's augmentations from the ORION Project.