Operation: ABLE SENTRY

Operation: ABLE SENTRY was an operation of the United Nations Space Command on Circinius IV during the Human-Covenant War between 2531 and 2552. The operation saw the deployment of a unit of UNSC Marines—including Edward Buck—to provide force reconnaissance for Operation: PHALANX, an operation carried out by Spartan-IIs to evacuate civilians and observe Covenant invasion patterns on the planet.