In the early 2490s the colony of Levosia was suspected of diverting refined selenium and technetium, elements which could be used to make FTL drives, to the black market. UNSC CENTCOM, desperate not to allow insurgent forces access to FTL drives, ordered the Navy to blockade and search all ships in the 26 Draconis system for contraband.
The Callisto stopped and boarded a trading vessel. The merchant crew was skittish due to rumors of impressments during similar searches in the Outer Colonies. A weapon was drawn and shots exchanged, resulting in the death of three naval officers and twenty-seven merchant crewmen. No contraband was ever discovered. This sparked outrage through out this system.
Thirty-seven days later the Callisto boarded another merchant vessel. They were courteously allowed aboard, however they found the cargo bay empty. The bay doors then opened and they were blasted into space. The merchant crew then swarmed into the Callisto, murdered the remainder of its crew, and gutted and replaced its computer system.
In response the UNSC dispatched a battle group three light destroyers - the Jericho, Buenos Aires and Las Vegas - to hunt down the renegade ship. Their crews and their weapons were inexperienced and untested.
On March 2, 2494, the battle group confronted the Callisto in the 26 Draconis system . The destroyers all fired six of their seven Ares missiles, and in response, the Insurrectionists maneuvered behind an asteroid, which it then detonated in the direction of the UNSC vessels using a nuclear warhead planted beforehand. The Buenos Aires was destroyed and the other two destroyers severely damaged. The entire bridge crew was killed or incapacitated, with the exception of Second Lieutenant Preston J. Cole, who was left unharmed. As the last remaining bridge officer, Cole took control of the Las Vegas.
Cole signaled the Callisto, declaring their surrender. However, he ordered the crewmen to remove the ship's last Ares missile from its silo and transport it to Cargo Bay 5. When the Callisto docked with the Las Vegas at Cargo Bay 5 the missile was fired directly into the corvette, crippling it and forcing its surrender.
- The ship is named for Callisto of Greek mythology, who was transformed into a bear. It may also be named for the Jovian moon which is also named for the mythological character.