From Halopedia, the Halo wiki
4 Charlie was a UNSC Army unit stationed on Reach during 2552. During the Fall of Reach on August 23, they fought in the Siege of New Alexandria, where 4 Charlie 27 and his team were sent to disable a Covenant communications jammer in Club Errera in the Vyrant Telecom Tower, alongside Troopers from 4 Delta. 4 Charlie 27 sent a distress call requesting assistance after encountering two pairs of Hunters. The Troopers were pinned down, low on ammunition and had taken multiple casualties when Spartan-B312 arrived to provide assistance, dispatching the Hunters and deactivating the jammer.
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