From Halopedia, the Halo wiki
In 2526, the Chaco was one of several vessels of Battle Group X-Ray assigned to Task Force Pantea, a task force of destroyers operating as a "wolf-pack" unit in the Outer Colonies. These task forces were deployed in the Outer Colonies to independently harass and destroy the supply lines of the invading Covenant fleets. At 21:00 hours on June 3, 2526, the Chaco was an element in the task force over Netherop when the destroyers encountered a lone Covenant frigate - the Steadfast Strike. The destroyers engaged the frigate, quickly eliminating the Strike's primary weapon systems and disabling the ship.
Following Steadfast Strike's crash-landing, the Chaco deployed two Pelican dropships to investigate the crash-site, though the craft were fired upon, with one craft soon shot down by the downed-frigate's pulse laser turrets.
Task Force Pantea was later ordered by Admiral Preston Cole to stay on-station to support Blue Team during their operation to recover the wreckage of Steadfast Strike, later engaging the Covenant Fleet of Swift Justice. It is unknown if the Chaco survived the battle.
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List of appearances