From Halopedia, the Halo wiki
While the Covenant fleet was glassing Etalan, a unit of the Silent Shadow, led by First Blade Tel 'Szatulai, arrived on Amasa to take a measure of the colony's defenses and search for hints of Forerunner artifacts. Aware that Amasa would be targeted by the Covenant, the United Rebel Front deployed a messenger to the world who located the Silent Shadow and delivered a transmission, before being slain by the Sangheili warriors. The transmission contained a message from Major General Harper Garvin, who proposed an alliance between the Covenant and URF to topple the Unified Earth Government. The Silent Shadow delivered the message to 'Kvarosee over Etalan, who sought to use the alliance as an opportunity to locate more human colonies.
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