2552 was a year during the Human-Covenant War, during which the humans of the United Nations Space Command nearly saw utter defeat and extinction.
A team of Orbital Drop Shock Troopers (including Kojo Agu and Taylor H. Miles) descend onto Ariel (a small science colony) in response to a distress call from the planet in Operation: FIRESIDE.
Insurrectionists on Harmony disable the planet's primary communications relay and steal two drydocked freifighters.
Battle of Fumirole: Nobel Team member Thom-293 destroys a CCS-class battlecruiser but kills himself in the process, and Catherine-B320 loses her arm. She subsequently recieves a robotic prosthetic replacement.
SPARTAN-B312 takes place on a counter-insurgency operation on Mamore. The SPARTAN's skills as a Sabre Pilot are exhibited during the op, prompting Colonel Urband Holland to have the SPARTAN transferred to Noble Team.
The Slipspace probes from the Archimedes encounter the Covenant Ships sent to attack Sigma Octanus IV.
The UNSC Iroquois is tasked with patrolling the Sigma Octanus Star System.
The Battle of Sigma Octanus IV begins.
The UNSC win a victory during the Battle at Sigma Octanus IV. Commander Jacob Keyes, of the UNSC Iroquois, plays a critical role in this success